Magnetoresistance effect element, magnetic head and magnetic recording and/or reproducing system

ABSTRACT

There is provided a practical magnetoresistance effect element which has an appropriate value of resistance, which can be sensitized and which has a small number of magnetic layers to be controlled, and a magnetic head and magnetic recording and/or reproducing system using the same. In a magnetoresistance effect element wherein a sense current is caused to flow in a direction perpendicular to the plane of the film, a resistance regulating layer is provided in at least one of a pinned layer, a free layer and an non-magnetic intermediate layer. The resistance regulating layer contains, as a principal component, an oxide, a nitride, a fluoride, a carbide or a boride. The resistance regulating layer may be a continuous film or may have pin holes. Thus, it is possible to provide a practical magnetoresistance effect element which has an appropriate value of resistance, which can be sensitized and which has a small number of magnetic layers, while effectively utilizing the scattering effect depending on spin.

CROSS REFERENCE TO RELATED APPLICATION

The present divisional application claims the benefit of priority under35 U.S.C. §120 to application Ser. No. 12/212,162, filed on Sep. 17,2008 which is a divisional of application Ser. No. 11/389,175, filed onMar. 27, 2006, which is a divisional of U.S. application Ser. No.11/080,485 (now U.S. Pat. No. 7,046,489), filed on Mar. 16, 2005, whichis a continuation of U.S. application Ser. No. 09/981,987 (now U.S. Pat.No. 6,937,446), filed on Oct. 19, 2001, and under 35 U.S.C. §119 fromJapanese Patent Application No. 2000-321171, filed on Oct. 20, 2000; theentire contents of each of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a magnetoresistance effectelement, a magnetic head and a magnetic recording and/or reproducingsystem. More specifically, the invention relates to a magnetoresistanceeffect element using a spin-valve film wherein a sense current flows ina direction perpendicular to the plane of the thin film, a magnetic headincluding the magnetoresistance effect element, and a magnetic recordingand/or reproducing system including the magnetoresistance effectelement.

2. Description of Related Art

There is known a phenomenon that an electric resistance varies inresponse to an external magnetic field in a certain kind offerromagnetic material. This is called a “magnetoresistance effect”.This effect can be used for detecting an external magnetic field, andsuch a magnetic field detecting element is called a magnetoresistanceeffect element (which will be hereinafter referred to as an “MRelement”)”.

Such an MR element is industrially utilized for reading information,which has been stored in a magnetic recording medium, in a magneticrecording and/or reproducing system, such as a hard disk or a magnetictape (see IEEE MAG-7, 150 (1971)), and such a magnetic head is called an“MR head”.

is being enhanced, and the size of one bit is decreasing, so that theamount of leakage flux from a bit is increasingly decreased. For thatreason, it is necessary to prepare an MR element, which has a highsensitivity and a high S/N ratio and which can obtain a high rate ofchange in resistance even in a lower magnetic field, in order to readinformation which has been written in a magnetic medium, and this is animportant basic technique for improving the recording density.

The “high sensitivity” means that the amount of change in resistance (Ω)per a unit magnetic field (Oe) is large. As an MR element has a largeramount of change in MR and a more excellent magnetically softcharacteristic, the MR element has a higher sensitivity. In addition, inorder to realize a high S/N ratio, it is important to reduce thermalnoises. Therefore, it is not desired that the resistance itself of theelement is too high, and when the element is used as a reading sensorfor a hard disk, the resistance of the element is preferably in therange of from about 5Ω to about 30Ω in order to realize a good S/Nratio.

Under such a background, at present, a spin-valve film capable ofobtaining a high rate of change in MR is generally used as an MR elementfor use in a hard disk MR head.

FIG. 25 is a conceptual drawing showing an example of a schematiccross-sectional structure of a spin-valve film. The spin-valve film 100has a structure wherein a ferromagnetic layer F, a non-magnetic layer S,a ferromagnetic layer P and an antiferromagnetic layer A are stacked inthat order. Of the two ferromagnetic layers F and P which aremagnetically in a non-coupled state via the non-magnetic layer S, themagnetization of one ferromagnetic layer P is fixed by an exchange biasor the like using the antiferromagnetic material, and the magnetizationof the other ferromagnetic layer F is set to be capable of being easilyrotated by an external magnetic field (a signal magnetic field or thelike). Then, only the magnetization of the ferromagnetic layer F can berotated by the external magnetic field to change a relative anglebetween the magnetization directions of the two ferromagnetic layers Pand F to obtain a large magnetoresistance effect (see Phys. Rev. B45,806 (1992), J. Appl. Phys. 69, 4774 (1991)).

The ferromagnetic layer F is often called a “free layer”, a “magneticfield receiving layer”, or a “magnetization free layer”. Theferromagnetic layer P is often called a “pinned layer” or a“magnetization fixed layer”. The non-magnetic layer S is often called a“spacer layer”, a “non-magnetic intermediate layer” or an “intermediatelayer”.

The spin-valve film can rotate the magnetization of the free layer,i.e., the ferromagnetic layer F. Therefore, the spin-valve film can besensitized, so that it is suitable for an MR element for use in an MRhead.

It is required to cause a “sense current” to flow through such aspin-valve element in order to detect the variation in resistance due toa magnetic field.

FIG. 26 is a conceptual drawing showing a generally used current supplysystem. That is, at present, there is generally used a system forproviding electrodes EL, EL on both ends of a spin-valve element asshown in the figure to cause a sense current I to flow in parallel tothe plane of the film to measure a resistance in a direction parallel tothe plane of the film. This method is generally called a“current-in-plane (CIP)” system.

In the case of the CIP system, it is possible to obtain a value of about10 to 20% as a rate of change in MR. In a shield-type MR head which isgenerally used at present, a spin-valve element has a substantiallysquare shape, so that the resistance of an MR element is substantiallyequal-to a value of plane electric resistance (sheet resistance) of anMR film. Therefore, a spin-valve film of a CIP system can obtain goodS/N characteristics if the value of plane electric resistance is set tobe 5 to 30Ω. This can be relatively simply realized by decreasing thethickness of the whole spin-valve film. Because of these advantages, thespin-valve film of the CIP system is generally used as an MR element foran MR head at present.

However, it is expected that the rate of change in MR is required toexceed 30% in order to realize information reproduction at a highrecording density exceeding 100 Gbit/inch². On the other hand, it isdifficult to obtain a value exceeding 20% as the rate of change in MR inconventional spin-valve films. For that reason, in order to furtherimprove a recording density, it is a great technical theme to increasethe rate of change in MR.

From such a point of view, in order to increase the rate of change inMR, there is proposed a spin-valve wherein an “electron reflectivelayer” of any one of oxides, nitrides, fluorides and borides is insertedinto a pinned layer and a free layer in a CIP-SV film.

FIG. 27 is a conceptual drawing showing the construction of a crosssection of such a spin-valve film. That is, in the construction shown inthis figure, an electron reflective layer ER is inserted into each of apinned layer P and a free layer F. If the scattering of electrons occurson the interfaces between respective layers in a spin-valve film, theapparent mean free path decreases, so that the rate of change in MRdecreases. On the other hand, if the electron reflective layer ER isprovided for causing electrons to reflect, it is possible to increasethe apparent mean free path of electrons to obtain a high rate of changein MR.

In addition, in this construction, the probability that electrons willpass through the interface of magnetic material/non-magnetic material isincreased by causing electrons to reflect, so that it is possible toapparently obtain the same effects as those of an artificial latticefilm to increase the rate of change in MR.

However, also in this construction, all of electrons do not always passthrough the interface of magnetic material/non-magnetic material, sothat there is a limit to the increase of the rate of change in MR. Forthat reason, also in the above described CIP-SV film wherein theelectron reflective layers are inserted, it is substantially difficultto realize a high rate of change in MR exceeding 20% and a practicalamount of change in resistance of 5 to 30 Ω.

On the other hand, as a method for obtaining a large MR exceeding 30%,there is proposed a magnetoresistance effect element (which will behereinafter referred to as a CPP-artificial lattice) of a type (currentperpendicular to plane (CPP)) that a sense current is caused to flow ina direction perpendicular to the plane of the film in an artificiallattice wherein magnetic and non-magnetic materials are stacked.

FIG. 28 is a conceptual drawing showing a cross-sectional structure of aCPP-artificial lattice type element. In a magnetoresistance effectelement of this type, electrodes EL are provided on the top and bottomface of an artificial lattice SL comprising ferromagnetic andnon-magnetic layers which are alternately stacked, and a sense current Iflows in a direction perpendicular to the plane of the film. It is knownthat this construction can a good interface effect and a high rate ofchange in MR since the-probability that the current I will cross theinterfaces between the magnetic layers and the non-magnetic layers.

However, in such a CPP artificial lattice type film, it is required tomeasure the electric resistance of an artificial lattice SL having thestacked structure of very thin metallic films in a directionperpendicular to the plane of the film. However, this value ofresistance is generally very small. Therefore, in the CPP artificiallattice, it is an important technical theme to increase the value ofresistance. Conventionally, in order to increase this value, it isnecessary to decreases the junction area between the artificial latticeSL and the electrode SL as small as possible and to increase the numberof stacked layers of the artificial lattice SL to increase the totalthickness of the film. For example, when the element is patterned so asto have a size of 0.1 μm×0.1 μm, if a Co layer having a thickness of 2nm and a Cu layer having a thickness of 2 nm are alternately stacked tentimes, the total thickness of the film is 20 nm, and a value ofresistance of about 1Ω can be obtained. However, it can not be said thatsuch a value of resistance is sufficiently a large value, so that it isrequired to further increase the number of the layers.

For the above described reasons, in order that the CPP artificiallattice type film provides a sufficient head output to be used as a goodreading sensor for a hard disk, it is necessary for the film to be theartificial lattice type, not the spin-valve type, from the standpoint ofresistance.

However, when the MR element is used for an MR head, it is required tocause each of magnetic layers to be a single magnetic domain so as notto generate Barkhausen noises and so forth, while controlling themagnetization of the magnetic layer so that an external magnetic fieldcan be efficiently measured. However, as described above, it is requiredto alternately stack many magnetic and non-magnetic layers in order toincrease the value of resistance in the CPP-MR element, and it istechnically very difficult to individually control the magnetization ofsuch many magnetic layers.

In addition, when the MR element is used for an MR head, it is requiredto allow the magnetization of a small signal magnetic field tosensitively rotate to obtain a high rate of change in MR. For thatpurpose, it is required to improve the signal magnetic flux density at asensing portion to obtain a large amount of rotation of magnetizationeven at the same magnetic flux density. Therefore, it is required todecrease the total Mst (magnetization×thickness) of layers whereinmagnetization is rotated by an external magnetic field. However, in theCPP-MR element, it is required to alternately stack many magnetic andnon-magnetic layers in order to increase the value of resistance.Therefore, the Mst increases, so that it is difficult to improve thesensitivity to the signal magnetic flux.

For that reason, although it is expected that the CPP artificial latticetype film has a rate of change in MR exceeding 30%, it is difficult tosensitize the film in order to use the film as an MR sensor for a head,so that it is substantially impossible to use the film as the MR sensor.

On the other hand, it is considered that the spin-valve structure usingFeMn/NiFe/Cu/NiFe, FeMn/CoFe/Cu/CoFe or the like adopts the CPP system.

FIG. 29 is a conceptual drawing showing a cross-sectional structure of aCPP-SV element. However, in such a CPP-SV construction, the thickness ofa magnetic layer must be increased to about 20 nm in order to increasethe value of resistance. Also in that case, it is predicted that therate of change in resistance would be only about 30% at 4.2 K and about15%, which is half thereof, at room temperatures.

That is, in the spin-valve film of the CPP system, the rate of change inMR is only about 15%, and the Mst of the free layer must be increased.Therefore, it is difficult to sensitize the film in order to use thefilm as an MR sensor for a head, so that it is substantially difficultto use the film.

As described above, although there are proposed various systems, such asthe spin-valve film of the CIP system, the artificial lattice of the CPPsystem, and the spin-valve of the CPP system. However, at present, themagnetic packing density is increasing at a rate of 60% or more everyyear, so that it will be requested to further increase the output infuture. However, at present, it is difficult to realize a spin-valvefilm which can be used at a high packing density exceeding 100Gbit/inch², which has an appropriate value of resistance and a largeamount of change in MR and which is magnetically sensitive.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to eliminate theaforementioned problems and to provide a practical magnetoresistanceeffect element which has an appropriate value of resistance, which canbe sensitized and which has a small number of magnetic layers to becontrolled, while effectively utilizing the scattering effect dependingon spin, and a magnetic head and magnetic recording and/or reproducingsystem using the same.

In order to accomplish the aforementioned object, according to a firstaspect of the present invention, a magnetoresistance effect elementcomprises: a magnetoresistance effect film including a magnetizationfixed layer having a ferromagnetic film in which the direction ofmagnetization is substantially fixed to one direction, a magnetizationfree layer having a ferromagnetic film in which the direction ofmagnetization varies in response to an external magnetic field, and annon-magnetic intermediate layer provided between the magnetization fixedlayer and the magnetization free layer; a pair of electrodes which areelectrically connected to the magnetoresistance effect film for applyinga current in a direction perpendicular to the plane of themagnetoresistance effect film; and a resistant regulating layer whichcontains an oxide, a nitride, a fluoride, a carbide or a boride as aprincipal component.

According to a second aspect of the present invention, amagnetoresistance effect element comprises: a magnetoresistance effectfilm including a magnetization fixed layer having a ferromagnetic filmin which the direction of magnetization is substantially fixed to onedirection, a magnetization free layer having a ferromagnetic film inwhich the direction of magnetization varies in response to an externalmagnetic field, and an non-magnetic intermediate layer provided betweenthe magnetization fixed layer and the magnetization free layer; a pairof electrodes which are electrically connected to the magnetoresistanceeffect film for applying a current in a direction perpendicular to theplane of the magnetoresistance effect film; and a resistant regulatinglayer for restricting the quantity of a sense current passing throughthe magnetoresistance effect film.

The resistance regulating layer may have pin holes at a rate of holearea which is 50% or less.

The resistance regulating layer may be made of two kinds or more ofmetallic elements.

The resistance regulating layer may be formed in the magnetization freelayer, or on the magnetization free layer on the opposite side to thenon-magnetic intermediate layer.

The resistance regulating layer may be formed in the non-magneticintermediate layer or on the interface of the non-magnetic intermediatelayer.

The resistance regulating layer may be formed in the magnetization fixedlayer, or on the magnetization fixed layer on the opposite side to thenon-magnetic intermediate layer.

The resistance regulating layer may contain, as a principal component,at least one of oxides, nitrides, fluorides, carbides or borides of anelement selected from the group consisting of B, Si, Ge, Ta, W, Nb, Al,Mo, P, V, As, Sb, Zr, Ti, Zn, Pb, Th, Be, Cd, Sc, La, Y, Pr, Cr, Sn, Ga,Cu, In, Rh, Pd, Mg, Li, Ba, Ca, Sr, Mn, Fe, Co, Ni and Rb.

The resistance regulating layer may be formed on the magnetization freelayer on the opposite side to the non-magnetic intermediate layer, or inthe non-magnetic intermediate layer, or on the interface of thenon-magnetic intermediate layer, and contain a metal including at leastone of Cu, Au, Ag, Ru, Ir, Re, Rh, Pt, Pd, Al and Os.

The resistance regulating layer may comprise: a first region which isformed on the magnetization free layer on the opposite side to thenon-magnetic intermediate layer, or in the non-magnetic intermediatelayer, or on the interface of the non-magnetic intermediate layer, andwhich contains Cu as a principal component; and a second region whichcontains, as a principal component, at least one of oxides, nitrides,fluorides, carbides and borides of an element selected from the groupconsisting of B, Fe, Mo, Pb, Ta, Cr, V, Si, Sb and Ge.

The resistance regulating layer may comprise: a first region which isformed on the magnetization free layer on the opposite side to thenon-magnetic intermediate layer, or in the non-magnetic intermediatelayer, or on the interface of the non-magnetic intermediate layer, andwhich contains Au as a principal component; and a second region whichcontains, as a principal component, at least one of oxides, nitrides,fluorides, carbides and borides of an element selected from the groupconsisting of B, Fe, Ge, Mo, P, Rh, Si, W and Cr.

The resistance regulating layer may comprise: a first region which isformed on the magnetization free layer on the opposite side to thenon-magnetic intermediate layer, or in the non-magnetic intermediatelayer, or on the interface of the non-magnetic intermediate layer, andwhich contains Ag as a principal component; and a second region whichcontains, as a principal component, at least one of oxides, nitrides,fluorides, carbides and borides of an element selected from the groupconsisting of Be, Co, Cr, Fe, Mo, Pb, Si, Ta, V, W, Ge, Sn, Al and Rh.

According to a third aspect of the present invention, amagnetoresistance effect element comprises: a magnetoresistance effectfilm including a magnetization fixed layer having a ferromagnetic filmin which the direction of magnetization is substantially fixed to onedirection, a magnetization free layer having a ferromagnetic film inwhich the direction of magnetization varies in response to an externalmagnetic field, and an non-magnetic intermediate layer provided betweenthe magnetization fixed layer and the magnetization free layer; a pairof electrodes which are electrically connected to the magnetoresistanceeffect film for applying a current in a direction perpendicular to theplane of the magnetoresistance effect film; and a region which is formedon the magnetization free layer on the opposite side to the non-magneticintermediate layer, or in the non-magnetic intermediate layer, or on theinterface of the non-magnetic intermediate layer, and which contains, asa principal component, a crystalline oxide containing at least oneselected from the group consisting of B, Si, Ge, W, Nb, Mo, P, V, Sb,Zr, Ti, Zn, Pb, Cr, Sn, Ga, Fe and Co.

The resistance regulating layer may have a thickness of 0.5 to 5 nm.

The resistance regulating layer may include holes of a metal phase of 2%to 30%.

The mean diameter of each of the holes of the resistance regulatinglayer may be in the range of from 5% to 100% with respect to the totalthickness of the magnetization free layer, the non-magnetic intermediatelayer and the magnetization fixed layer.

The mean distance between adjacent two of the holes of the metal phasemay be in the range of from 10 nm to 100 nm.

According to a fourth aspect of the present invention, there is provideda magnetic head having any one of the above described magnetoresistanceeffect elements.

According to a fifth aspect of the present invention, there is provideda magnetic recording and/or reproducing system which has the abovedescribed magnetic head and which is capable of reading magneticinformation stored in a magnetic recording medium.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood more fully from the detaileddescription given herebelow and from the accompanying drawings of theembodiments of the invention. However, the drawings are not intended toimply limitation of the invention to a specific embodiment, but are forexplanation and understanding only.

In the drawings:

FIG. 1 is a conceptual drawing showing a cross-sectional structure ofthe first embodiment of a magnetoresistance effect element according toan aspect of the present invention;

FIG. 2A is a graph showing potentials sensed by electrons in the casesof up-spin and down-spin when the magnetization of a pinned layer P isparallel to the magnetization of a free layer F, and FIG. 2B is a graphshowing potentials sensed by electrons in the cases of up-spin anddown-spin when the magnetization of the pinned layer P is anti-parallelto the magnetization of the free layer F;

FIG. 3A is a graph showing potentials sensed by electrons in the casesof up-spin and down-spin when the magnetization of the pinned layer isparallel to the magnetization of the free layer, and FIG. 3B is a graphshowing potentials sensed by electrons in the cases of up-spin anddown-spin when the magnetization of the pinned layer is anti-parallel tothe magnetization of the free layer;

FIG. 4 is a conceptual drawing showing a cross-sectional structure of amagnetoresistance effect element in this embodiment;

FIG. 5A is a sectional view showing the construction of amagnetoresistance effect element wherein the positions of pin holes Hare the same between upper and lower resistance regulating layers R1 andR2, and FIG. 5B is a sectional view showing the construction of amagnetoresistance effect element wherein the positions of pin holes Hare shifted between upper and lower resistance regulating layers R1 andR2;

FIG. 6 is a conceptual drawing showing the construction of amagnetoresistance effect element which includes two or more resistanceregulating layers R1A, R1B or R2A, R2B;

FIG. 7 is a conceptual drawing showing the construction of amagnetoresistance effect element wherein a resistance regulating layeris sandwiched between non-magnetic layers NM1 and NM2 without beinginserted into a ferromagnetic layer FM;

FIG. 8 is a conceptual drawing showing the construction of amagnetoresistance effect element which adopts a stacked structure offerromagnetic films FM and non-magnetic films NM;

FIG. 9 is a conceptual drawing showing the construction of amagnetoresistance effect element which adopts a stacked film of twokinds or more of ferromagnetic materials;

FIG. 10 is a conceptual drawing illustrating the construction of amagnetoresistance effect element wherein ferromagnetic layerssandwiching resistance regulating layers comprises two or more kinds offerromagnetic layers;

FIG. 11 is a conceptual drawing showing the construction of amagnetoresistance effect element wherein a ferromagnetic layer FM (fcc)having the fcc structure and a ferromagnetic layer FM (bcc) having thebcc structure are combined;

FIG. 12 is a conceptual drawing showing the construction of amagnetoresistance effect element wherein non-magnetic layers NM have astacked structure of first and second non-magnetic layers NM1 and NM2;

FIG. 13 is a conceptual drawing showing the construction of amagnetoresistance effect element which adopts a stacked structure offerromagnetic layer FM1/ferromagnetic layer FM2;

FIG. 14 is a conceptual drawing showing another example of amagnetoresistance effect element which has a plurality of ferromagneticlayers;

FIG. 15 is a conceptual drawing showing another example of amagnetoresistance effect element which has a plurality of ferromagneticlayers;

FIG. 16 is a conceptual drawing showing the construction of amagnetoresistance effect element having a so-called syntheticantiferromagnetic structure;

FIG. 17 is a conceptual drawing showing the construction of amagnetoresistance effect element which adopts an underlying layer(buffer layer) B and a protective layer C;

FIG. 18 is a conceptual drawing showing a cross-sectional structure ofthe second embodiment of a magnetoresistance effect element according toan aspect of the present invention;

FIG. 19 is a conceptual drawing showing-the construction of amagnetoresistance effect element wherein pin holes are arranged at thesame place between the respective resistance regulating layers;

FIG. 20 is conceptual drawing showing the construction of amagnetoresistance effect element wherein the positions of pin holes areshifted between the respective resistance regulating layers;

FIG. 21 is a conceptual drawing showing a cross-sectional constructionof a principal part of a first example of a magnetoresistance effectelement according to an aspect of the present invention;

FIG. 22 is a schematic perspective view showing the construction of aprincipal part of a magnetic head using a magnetoresistance effectelement according to an aspect of the present invention;

FIG. 23 is a perspective view of a principal part illustrating aschematic construction of a magnetic recording and/or reproducing systemaccording to an aspect of the present invention;

FIG. 24 is an enlarged perspective view of a magnetic head assembly infront of an actuator arm 155, viewed from the side of a disk;

FIG. 25 is a conceptual drawing illustrating a schematic cross-sectionalstructure of a spin-valve film;

FIG. 26 is a conceptual drawing showing a generally used current supplysystem;

FIG. 27 is a conceptual drawing showing a cross-sectional constructionof a spin-valve film;

FIG. 28 is a conceptual drawing showing a cross-sectional structure of aCPP-artificial lattice type element;

FIG. 29 is a conceptual drawing showing a cross-sectional constructionof a CPP-SV element;

FIG. 30 is an illustration for explaining the construction and operationof an example of a resistance regulating layer;

FIG. 31 is a sectional view showing the construction of the thirdembodiment of a magnetoresistance effect element according to an aspectof the present invention;

FIG. 32 is a sectional view showing the construction of a modifiedexample of the third embodiment;

FIG. 33 is a sectional view showing the construction of the fourthembodiment of a magnetoresistance effect element according to an aspectof the present invention;

FIG. 34 is a sectional view showing the construction of a modifiedexample of the fourth embodiment;

FIG. 35 is a sectional view showing the construction of a modifiedexample of the fourth embodiment; and

FIG. 36 is a sectional view showing the construction of a modifiedexample of the fourth embodiment.

DESCRIPTION OF THE EMBODIMENTS

Referring now to the accompanying drawings, the embodiments of thepresent invention will be described below.

First Embodiment

FIG. 1 is a conceptual drawing showing a cross-sectional structure ofthe first embodiment of a magnetoresistance effect element according toan aspect of the present invention. That is, the magnetoresistanceeffect element 10A according to the aspect of the present inventioncomprises an antiferromagnetic layer A, a first magnetic layer P, annon-magnetic intermediate layer S and a second magnetic layer F whichare stacked on a predetermined substrate (not shown) in that order. Inaddition, a resistance regulating layer R1 is inserted into the firstmagnetic layer P, and a resistance regulating layer R2 is inserted intothe second magnetic layer F. Furthermore, the antiferromagnetic layer A,the first magnetic layer P, the non-magnetic intermediate layer S andthe second magnetic layer F constitute a magnetoresistance effect film.

Moreover, electrode layers EL are provided on the top and bottom facesof this stacked structure, respectively, and a sense current I is causedto flow in a direction perpendicular to the plane of the film.

In this embodiment, the first magnetic layer P functions as a “pinnedlayer”, the magnetization of which is fixed by one-directionalanisotropy due to the antiferromagnetic layer A. In addition, the secondmagnetic layer F functions as a “magnetic field receiving layer or freelayer”, the magnetization of which is rotated by an external magneticfield (e.g., a magnetic field due to signal) produced from a magneticrecording medium (not shown).

The first magnetic layer P and the second magnetic layer F include theresistance regulating layers R1 and R2, respectively, and have stackedstructures of ferromagnetic layer FM/resistance regulating layer R1 orresistance regulating layer R2/ferromagnetic layer FM, respectively. Inthis structure, the ferromagnetic layers on both sides of the resistanceregulating layer R1 or R2 are ferromagnetically coupled to each other,and the magnetization thereof behaves so as to be substantiallyintegrated. That is, the magnetization of each of the ferromagneticlayers included in this stacked structure of ferromagneticlayer/resistance regulating layer/ferromagnetic layer is substantiallyparallel to each other, the magnetization in the pinned layer (the firstmagnetic layer P) being substantially fixed in the same direction, andthe magnetizing direction in the free layer (the second magnetic layerF) being substantially the same direction with respect to the externalmagnetic field.

In this embodiment, a current I is designed to flow from the topelectrode EL toward the bottom electrode EL, and the resistanceregulating layers R1 and R2 are designed to cause the current to flow ina thickness direction while reducing the quantity of the current. Thatis, the resistance regulating layers R1 and R2 function as “filterlayers” for restricting the quantity of the sense current I passingtherethrough, or “current constriction layers” for allowing part ofconduction electrons forming the sense current I to be transmittedtherein, or “barrier layers” for reducing the quantity of the sensecurrent I. Referring to FIG. 30, the construction and operation of anexample of the above described resistance regulating layer will bedescribed below. If the resistance regulating layer R is sandwichedbetween films 20 and 21 constituting a magnetoresistance effect film andif electrodes EL1 and EL2 are connected to these films, respectively,when a current is caused to flow in a direction perpendicular to theplane of the film, the current passes through pin holes H as shown bybroken lines in FIG. 30, so that the quantity of current is reduced andresistance is increased. Furthermore, as will be described later, theconstruction and function of the resistance regulating layer should notbe limited thereto.

Moreover, part of the reduced current I flows between the two resistanceregulating layers R1 and R2 while repeatedly reflecting therebetween.However, the quantity of current flowing while repeatedly reflecting isnot so large with respect to the whole sense current. However, theprobability that electrons will pass through the CPP spin-valvestructure without reflection is slightly reduced by the reflection, sothat it is possible to further increase the electric resistance.Furthermore, these resistance regulating layers have morphologicallydifferent constructions from the electron reflective layer of the CIPspin-valve element.

In the CPP spin-valve film, the effect of the scattering of electrons onthe interface of ferromagnetic layer/non-magnetic layer, i.e., theinterface resistance, has a large spin dependency and serves to increasethe CPP-MR. In addition, the interface resistance tends to have arelatively large value. These characteristics are the same as the abovedescribed functions in the CPP artificial lattice referring to FIG. 28.

Therefore, the value of resistance in a direction perpendicular to theplane of the film can be increased by providing the resistanceregulating layers. As a result, according to the embodiment of thepresent invention, it is possible to utilize a larger number of valuesof interface resistance, so that it is possible to realize a CPP-SVhaving a higher resistance and a higher rate of change in MR than thoseof conventional CPP spin-valve films.

In addition, since this embodiment adopts the CPP system wherein acurrent I flows in a direction perpendicular to the plane of the film,all of the current I crosses the interfaces of ferromagneticlayers/non-magnetic layers. As a result, it is possible to veryeffectively utilize the interface effect which can not effectively beutilized in the case of the CIP system. For that reason, it is possibleto very conspicuously obtain the function of increasing the rate ofchange in MR which can not so sufficiently be obtained by the CIPconstruction.

By the above described effects, it is possible to provide a CPPspin-valve film suitably utilizing an interface resistance and having anappropriate value of resistance though it has a spin-valve construction.

In addition, in this embodiment, since the magnetization of the pinnedlayer P and the magnetization of the free layer F are operated so as tobe integrated, the magnetization can be controlled only by themagnetization fixed of the pinned layer P and the control of themagnetization of one free layer F. Therefore, when the element is usedfor a reading sensor, such as a magnetic head, it is possible to realizea magnetic head wherein Barkhausen noises are suppressed.

In addition, in this embodiment, it is possible to obtain a good valueof resistance and a good rate of change in MR while the total thicknessof the pinned layer P and free layer F is small. That is, as comparedwith the simple CPP spin-valve construction, this construction canreduce the simple transmission probability of electrons, increase thevalue of resistance and sufficiently utilize the interface resistance.Therefore, even if the total Mst of the pinned layer P and free layer Fis small, it is possible to obtain a sufficient value of resistance anda sufficient rate of change in MR.

Specifically, although the thickness of the magnetic material of thepinned layer P and free layer F must be about 20 nm in conventionalconstructions, this embodiment can obtain sufficient characteristicseven if the total thickness of the magnetic layers is 5 nm or less.Thus, the Mst of the free layer F can be held to be a small value, sothat it is possible to realize a sensitive spin-valve element. Inaddition, since it is possible to decrease the Mst of the pinned layerP, it is possible to improve the magnetization fixed characteristics bythe antiferromagnetic layer A, so that it is possible to improve thereliability of the device.

In this embodiment, the resistance regulating layers R1 and R2 may beformed of a semimetal, such as Bi (bismuth), Sb (antimony) or C(carbon), or a so-called zero gap semiconductor, such as ZnSe (zincselenide). In these materials unlike insulating materials, conductionelectrons exist, but the density thereof is vary small, so thatpotential sensed by the conduction electrons is vary small.Specifically, a metal, such as Cu (copper), has a Fermi potential ofabout 7 eV, whereas a semimetal has a small Fermi potential of 1 eV orless.

For that reason, if the resistance regulating layers R1 and R2 of asemimetal or a zero gap semiconductor are provided in a metal layerserving as a ferromagnetic material, large differences in potentiallevel occur as illustrated in FIGS. 2A and 2B, so that the transmissionof conduction electrons is restricted. Furthermore, FIG. 2A is a graphshowing potentials sensed by electrons in the cases of up-spin anddown-spin when the magnetization of the pinned layer P is parallel tothe magnetization of the free layer F, and FIG. 2B is a graph showingpotentials sensed by electrons in the cases of up-spin and down-spinwhen the magnetization of the pinned layer P is anti-parallel to themagnetization of the free layer F.

In the construction according to the embodiment of the presentinvention, since conduction electrons also exist in the resistanceregulating layers R1 and R2, the conduction probability of conductionelectrons is sufficiently larger than the transmission probability ofelectrons due to tunnel, so that the usual conduction controls the totalvalue of resistance. For that reason, it is possible to make resistancelower than that in the case of a ferromagnetic tunnel junction, so thatit is possible to obtain a good element resistance in a fine junction.

The value of Fermi potential in these materials is preferably in therange of from 1 eV to 0 eV, and more preferably in the range of 0.5 eVto 0 eV. The first one of the reasons for this is that, in thesematerials, the difference in potential level sensed by electrons can beincreased as the value of Fermi potential is decreased, so that thetransmission probability of electrons can be small. In addition, sincethe number of conduction electrons in the semimetal is decreased, thetransmission probability of electrons can be very small. In the case of0.5 eV, the number of conduction electrons is about 3.5×10²⁰, which issmaller than that in a noble metal, such as Cu, by about two digits, sothat it is possible to greatly increase resistance. Therefore, the valueof Fermi potential in these materials is preferably 0.5 eV or less.However, if it is 1 eV or less, the number of conduction electrons isabout 4.6×10²¹, which is smaller than that in a noble metal, such as Cu,by about one digit, so that it is possible to sufficiently increaseresistance.

The resistance regulating layers R1 and R2 in this embodiment may bealso formed of Au (gold), Ag (silver) or an alloy thereof. However, inthis case, it is difficult to form so great difference in potentiallevel, so that it is not easy to greatly increase resistance.

The resistance regulating layers R1 and R2 in this embodiment may bealso formed of an insulating material which has a potential barrierhaving a relatively low height. FIGS. 3A and 3B are potential diagramscorresponding to this construction. That is, FIG. 3A is a graph showingpotentials sensed by electrons in the cases of up-spin and down-spinwhen the magnetization of the pinned layer is parallel to themagnetization of the free layer, and FIG. 3B is a graph showingpotentials sensed by electrons in the cases of up-spin and down-spinwhen the magnetization of the pinned layer is anti-parallel to themagnetization of the free layer.

In this example, the transmission probability of electrons is determinedby the tunnel probability of electrons in the resistance regulatinglayers R1 and R2. Therefore, since the element resistance is too high ifthe barrier height increases, the barrier height of the resistanceregulating layers R1 and R2 is preferably 0.1 eV or less.

On the other hand, the resistance regulating layers R1 and R2 in thisembodiment may be formed of an insulating material having pin holes. Inthis case, the transmission probability of electrons is determined bythe size and density of pin holes. FIG. 4 is a conceptual drawingshowing the cross-sectional construction in this example. As shown inthis figure, the resistance regulating layers R1 and R2 may suitablyhave pin holes H. If the size of the pin holes H is about the mean freepath of electrons or less, it is possible to obtain a greater resistanceincreasing effect. From the standpoint of repeatability of elementcharacteristics, at least 10 or more pin holes H are preferably formedin the films of the element. However, only one pin hole H may exist inthe element. The ratio of the total area of the pin holes H to the areaof the film of the element may be suitably determined, and is preferably50% or less in order to increase the element resistance.

In the example of FIG. 4, the transmission probability of electrons isdetermined by the electric conduction through the pin holes H.Therefore, the resistance regulating layers R1 and R2 may be formed ofan insulating material having a high barrier height, e.g., Al (aluminum)oxide or Si (silicon) oxide. However, the resistance regulating layersR1 and R2 may be formed of a material having a low barrier height, suchas Co (cobalt) oxide, Ni (nickel) oxide or Cu (copper) oxide. Also inthat case, the electric conduction is mainly controlled by the pin holesH.

The thickness of the resistance regulating layers R1 and R2 in theexample of FIG. 4 can be suitably determined, and is preferably set tobe in the range of from 0.5 nm to 10 nm in order to surely and easilyform the pin holes H.

It is not particularly required to control the positions of the pinholes H in the resistance regulating layers R1 and R2 of the pinnedlayer P and free layer F. In this case, it is possible to obtainelectric conduction through the pin holes H which are formed at random.

Such resistance regulating layers R1 and R2 having pin holes H may beformed by a method for forming a very thin layer of, e.g., Al, which hasformed by the sputtering method or the like, and then, exposing thelayer to an atmosphere of oxygen for a short period of time to carry outa natural oxidation. Alternatively, the resistance regulating layers R1and R2 having the pin holes H may be formed by a method for applyingenergy to a vary thin layer of Al or the like by exposing it to oxygenplasma or irradiating it with oxygen ions or oxygen radicals.

Alternatively, a material which is relatively easy to be oxidized, and amaterial which is difficult to be oxidized, such as Al—Co, may besimultaneously deposited to form a granular film of Al—Co as a layer tobe oxidized, and the formed layer may be exposed to selectively oxidizeonly Al to form the resistance regulating layers R1 and R2 having thepin holes H.

Alternatively, the oxidized layer having pin holes H may be formed bydepositing a film in an atmosphere of oxygen.

As another method for forming such resistance regulating layers R1 andR2 having pin holes H, regularly arranged pinholes H may be formed bythe fine pattern lithography using the AFM (atomic force microscope) orthe like or by the self-organizing. In the case of the fine patternlithography using the AFM or the like, continuous films of, e.g., AlOx(aluminum oxide), may be formed, and holes may be formed therein. Whenregularly arranged pin holes are formed by the self-organizing, the pinholes may be formed by forming continuous films of, e.g., AlOx, applyingthereon a resist, in which pin holes can be formed by theself-organizing, and removing AlOx from the pin hole portion by themilling or RIE. Alternatively, an insulating material having pin holes Harranged by the self-organizing may be directly formed.

When pin holes H are formed by such a controlled method, the positionalrelationship between the pin holes H in the two resistance regulatinglayers R1 and R2 is important. That is, the pin holes H in the upper andlower resistance regulating layers R1 and R2 may be positioned at thesame place as illustrated in FIG. 5A. Alternatively, the positions ofthe pin holes H in the upper and lower resistance regulating layers R1and R2 may be shifted as illustrated in FIG. 5B. When the positions areshifted as illustrated in FIG. 5B, it is possible to more effectivelyreduce the quantity of current, so that it is possible to realize a CPPspin-valve element having a higher resistance.

When the pin holes H are formed by the controlled method, therelationship between the sizes of the pin holes H in the two resistanceregulating layers R1 and R2 can be also adjusted. That is, the sizes ofthe pin holes H in the upper and lower resistance regulating layers R1and R2 may be equal to or different from each other. If the size of thepin hole H in the electron entering resistance regulating layer of theresistance regulating layers R1 and R2 is greater than the size of thepin hole H in the other electron leaving regulating layer, it ispossible to more effectively reduce the quantity of current, so that itis possible to form a CPP spin-valve element having a higher resistance.

Each of the resistance regulating layers R1 and R2 in the stackedstructure of ferromagnetic layer/electron reflective layer must notalways comprise only one layer, and may include two or more resistanceregulating layers R1A and R1B or resistance regulating layers R2A andR2B as illustrated in FIG. 6. By thus inserting the plurality ofresistance regulating layers, it is possible to further reduce thesimple transmission probability of electrons, so that it is possible torealize a CPP-SV having a higher resistance.

On the side of the free layer F, the resistance regulating layer R2 maybe sandwiched between non-magnetic layers NM1 and NM2 without beinginserted into the ferromagnetic layer FM as illustrated in FIG. 7. Thus,it is possible to minimize the influence of the resistance regulatinglayer R2 on the magnetic characteristics of the free layer F, so that itis easy to be compatible with magnetically soft characteristics.

The ferromagnetic layers included in the above described first andsecond ferromagnetic layers P and F in this embodiment may be formed of,e.g., a simple substance of Co, a Co containing ferromagnetic material,an Ni base alloy such as NiFe alloy, or an Fe base alloy.

In this embodiment, the Fe base alloy is preferably a material which caneasily obtain magnetically soft characteristics, such as Fe (iron), FeNi(iron nickel), FeCo (iron cobalt), FeSi (iron silicon), FeMo (ironmolybdenum), or FeAl (iron aluminum).

The Co containing alloy may be an alloy of Co, to which one or more ofFe (iron, Ni (nickel, Au (gold), Ag (silver), Cu (copper), Pd(palladium), Pt (platinum), Ir (iridium), Rh (rhodium), Ru (ruthenium),Os (osmium) and Hf (hafnium) are added.

The amount of the additional element is preferably in the range of from5 to 50 at %, and more preferably in the range of from 8 to 20 at %.Because there is the possibility that the bulk effect does notsufficiently increase if the amount of the additional element is toosmall and that the interface effect greatly decreases if the amount ofthe additional element is too large. In order to obtain a high rate ofchange in MR, the additional element is preferably Fe.

The ferromagnetic layers included in the first and second magneticlayers P and F in this embodiment may have a stacked structure offerromagnetic layers FM and non-magnetic layers NM as illustrated inFIG. 8.

In this stacked structure of ferromagnetic layers FM/non-magnetic layersNM, the ferromagnetic layers FM sandwiching the non-magnetic layer NMtherebetween are ferromagnetically coupled to each other, and themagnetization is substantially parallel to each other and substantiallyarranged in the same direction.

If the pinned layer P and the free layer F comprise films having thestacked structure illustrated in FIG. 8, electrons pass through a largernumber of interfaces of ferromagnetic layers/non-magnetic layers. In theCPP spin-valve film, the effect of the scattering of electrons on theinterfaces of ferromagnetic layers/non-magnetic layers, i.e., theinterface resistance, has a large spin dependency and serves to increasethe CPP-MR. In this example, it is possible to utilize a larger numberof values of interface resistance, so that it is possible to obtain ahigher resistance and a higher rate of change in resistance.

Furthermore, in FIG. 8, a high conductive layer G having a high electricconductivity is provided between the free layer F and the electrode EL.

The insertion of the resistance regulating layers R1 and R2 particularlyhas an effect on the increase of the resistance of the CPP spin-valvefilm, and the stacking of the pinned layer P and free layer Fparticularly has an effect on the increase the rate in MR. For thatreason, by combining the two, it is possible to obtain a CPP spin-valvefilm which particularly has a high resistance and a high rate of changein MR.

As the film of the stacked structure of ferromagnetic layersFM/non-magnetic layers NM in this example, a large spin dependentinterface resistance is preferably obtained on the interfaces ofmagnetic layers FM/non-magnetic layers NM. With respect to suchcombinations of ferromagnetic and non-magnetic materials, theferromagnetic layers FM are preferably formed of an Fe base alloy, a Cobase alloy or an Ni base alloy, and the non-magnetic layers NM arepreferably formed of Cu, Ag, Au or an alloy thereof.

Alternatively, the non-magnetic layers NM may be particularly formed ofa non-ferromagnetic metal, such as Rh (rhodium), Ru (ruthenium), Mn(manganese), Cr (chromium), Re (rhenium), Os (osmium) or Ir (iridium).In particular, the non-magnetic layers NM is preferably formed of Mn orRe.

The combinations providing a particularly large interface resistance, ofthese combinations, include Fe base alloy/Au, Fe base alloy/Ag, or Febase alloy/Au—Ag alloy interface, Co base alloy/Cu, Co base alloy/Ag, Cobase alloy/Au, or Co base alloy/Cu—Ag—Au alloy interface.

The thickness of the ferromagnetic layer FM included in the stackedstructure of ferromagnetic layers FM/non-magnetic layers NM ispreferably as thin as possible, in order to increase the magneticstability of the pinned layer P and in order to decrease the Mst of thefree layer F to sensitize it. The upper limit of the thickness ispreferably 2 nm or less in order to increase the number of interfaces.

On the other hand, in order to suitably obtain the interface resistance,the combination of materials forming the stacked structure offerromagnetic layers FM/non-magnetic layers NM is preferably acombination of non-solid-solution systems. That is the materials of theferromagnetic layers FM and non-magnetic layers NM are not soluble ineach other. However, it is not always required to be limited tocombinations of non-solid-solution systems, in accordance with therequired level.

The ferromagnetic layers FM in the stacked structure of ferromagneticlayers FM/non-magnetic layers NM in this example are not always requiredto be formed of one kind of material, but the ferromagnetic layers FMmay be formed of a stacked film of two kinds or more of ferromagneticmaterials. That is, in the example shown in FIG. 9, each of the pinnedlayer P and the free layer F has a construction wherein a firstferromagnetic layer FM1, a second ferromagnetic layer FM2 and a thirdferromagnetic layer FM3 are stacked. However, the kind and number of theferromagnetic layers, or the stacking order should not be limited tothose in the figure.

For example, in the pinned layer P, an Fe/Au interface having a highinterface resistance is preferably used. However, since Fe has a largefluctuation in spin, it is desired to inhibit the fluctuation in spin,in order to use it at room temperatures. For that reason, theferromagnetic layers preferably have the stacked structure of Fe and amagnetic material, which has a small fluctuation in spin, such asFe/CoFe/Fe or Fe/NiFe/Fe.

On the other hand, also in the free layer F, the Fe/Au interface havinga high interface resistance is preferably used. However, it is difficultto obtain magnetically soft characteristics, which are required for thefree layer, by only Fe. Therefore, the ferromagnetic layers preferablyhave the stacked structure of Fe and a magnetic material, which hasexcellent magnetically soft characteristics, such as Fe/CoFe/Fe orFe/NiFe/Fe.

Also, the ferromagnetic layers in the stacked structure of ferromagneticlayers/resistance regulating layers are not always required to be formedof one kind of material.

FIG. 10 is a conceptual drawing illustrating the construction of amagnetoresistance effect element wherein ferromagnetic layerssandwiching resistance regulating layers comprises two or more kinds offerromagnetic layers. That is, in the example shown in this figure, eachof the pinned layer P and the free layer F has a first ferromagneticlayer FM1 and a second ferromagnetic layer FM2.

For example, although an Fe/Au interface having a high interfaceresistance is preferably used in the free layer F, it is difficult toobtain magnetically soft characteristics, which are required for thefree layer, by only Fe. On the other hand, it is possible to improvemagnetically soft characteristics by adding a magnetic layer of amagnetic material having excellent magnetically soft characteristics,such as CoFe or NiFe, which is ferromagnetically coupled as aferromagnetic layer.

In addition, when the ferromagnetic layers FM in the stacked structureof ferromagnetic layers FM/non-magnetic layers NM contain Fe or an Febase alloy, the crystal structure thereof is preferably theface-centered cubic (fcc) structure. Because the stacked structure canbe more stable when a metal having the fcc structure, such as Au, Ag orCu, is stacked and because the stacked structure can have goodcrystalline properties as a whole to improve magnetically softcharacteristics and reduce fluctuation in spin. However, the bccstructure can also be used.

In particular, when two kinds of ferromagnetic materials are combined asthe ferromagnetic layers in the stacked structure of ferromagneticlayers/non-magnetic layers, a ferromagnetic layer FM(fcc) having the fccstructure can be combined with a ferromagnetic layer FM(bcc) having thebcc structure as illustrated in FIG. 11. In such a combination, thestate of electrons, the shape of the Fermi surface, and the distributionof state density of the ferromagnetic material FM(fcc) having the fccstructure are greatly different from those of the ferromagnetic materialFM(bcc) having the bcc structure. For that reason, it is possible toobtain a considerable screen effect with respect to conductionelectrons, so that it is possible to obtain a high resistance and a highrate of change in MR. As shown in the figure, the first magnetic layer Pmay be formed of ferromagnetic layers having the bcc structure, and thesecond magnetic layer F may be formed of ferromagnetic layers havingthe-fcc structure. Even if the pinned layer P and free layer F thus havedifferent crystal structures, it is possible to obtain a large screeneffect.

In addition, according to an aspect of the present invention, theferromagnetic layers must be ferromagnetically coupled to each other inthe stacked structure of ferromagnetic layers/non-magnetic layersconstituting the pinned layer P and free layer F. For that purpose, itis required to form a good stacked structure. In addition, the magneticcharacteristics of the pinned layer P and free layer F can be improvedby adjusting the crystal lattice constant in the stacked structure to bethe optimum value. Therefore, the non-magnetic layers NM can also have astacked structure of, e.g., a first non-magnetic layer NM1 and secondnon-magnetic layers NM2 as illustrated in FIG. 12. For example, if thenon-magnetic layers NM have a stacked structure of Au layer/Cu layer/Aulayer, it is possible to realize a good lattice constant while realizinga high interface resistance, and it is possible to obtain good magneticcharacteristics.

The ferromagnetic layers FM included in the first and second magneticlayers P and F according to the present invention may have a stackedstructure of ferromagnetic layers FM1/ferromagnetic layers FM2 asillustrated in FIG. 13. In this stacked structure of ferromagneticlayers FM1/ferromagnetic layers FM2, the ferromagnetic layers areferromagnetically coupled to each other, and the magnetization issubstantially parallel to each other and substantially arranged in thesame direction.

If the pinned layer P and the free layer F comprise films having such astacked structure, electrons pass through a larger number of interfacesof ferromagnetic layers/ferromagnetic layers. In the CPP spin-valvefilm, the effect of the scattering of electrons on the interfaces offerromagnetic layers ferromagnetic layers, i.e., the interfaceresistance, has a large spin dependency and serves to increase theCPP-MR. In this example, it is possible to utilize a larger number ofvalues of interface resistance, so that it is possible to obtain ahigher resistance and a higher rate of change in resistance.

The insertion of the resistance regulating layers R1 and R2 particularlyhas an effect on the increase of the resistance of the CPP spin-valvefilm, and the stacking of the pinned layer P and free layer Fparticularly has an effect on the increase the rate in MR. For thatreason, by combining the two, it is possible to obtain a CPP spin-valvefilm which particularly has a high resistance and a high rate of changein MR.

In this example, a large number of interfaces of ferromagneticlayers/ferromagnetic layers can be arranged in the pinned layer P andfree layer F, and it is possible to utilize a larger number of values ofinterface resistance, so that it is possible to form a CPP-SV having ahigh resistance and a high rate of change in MR.

In addition, since the magnetization of the pinned layer P and themagnetization of the free layer F are operated so as to be integrated,the magnetization can be controlled only by the magnetization fixed ofthe pinned layer P and the control of the magnetization of one freelayer F. Therefore, when the element is used for a reading sensor, suchas a magnetic head, it is possible to realize a magnetic head whereinBarkhausen noises are suppressed.

Each of the ferromagnetic layers constituting the stacked structure offerromagnetic layers/ferromagnetic layers in this example may be formedof, e.g., a simple substance of Co, a Co containing ferromagneticmaterial such as a Co containing magnetic alloy, a ferromagneticmaterial such as NiFe alloy, or an Fe base alloy.

As a combination in which the interface resistance is particularly high,any one of NiFe alloy/CoFe alloy, Fe base alloy/NiFe alloy, and Fe basealloy/CoFe alloy is preferably used.

The thickness of the ferromagnetic layer included in the stackedstructure of ferromagnetic layers/ferromagnetic layers is preferably asthin as possible, in order to increase the number of interfaces withoutincreasing the total Mst. In a combination capable of holding magneticproperties, the ferromagnetic layer may be a monatomic layer. The upperlimit of the thickness is preferably 2 nm or less, in order to increasethe number of interfaces.

On the other hand, the thickness of the ferromagnetic layer included inthe stacked structure of ferromagnetic layers/ferromagnetic layers ispreferably 1 nm or less, in order to increase the number of interfacesas much as possible. Even if the ferromagnetic layer comprises amonoatomic layer as the lower limit thereof, it is possible to produceinterface resistance.

In order to suitably obtain the interface resistance, the combination ofmaterials forming the stacked structure of ferromagneticlayers/ferromagnetic layers is preferably a combination ofnon-solid-solution systems. However, the combination should not alwaysbe limited to the combination of non-solid-solution systems, and thecombination can be suitably determined.

FIG. 14 is a conceptual drawing showing another example where the pinnedlayer or the free layer has a plurality of ferromagnetic layers. Thatis, in the example shown in this figure, each of the pinned layer P andthe free layer F has the stacked structure of first ferromagnetic layersFM1 and second ferromagnetic layers FM2, and a third ferromagnetic layerFM3 is provided in the vicinity of each of the electron reflectivelayers R1 and R2.

For example, in the free layer F, the Fe/CoFe interface having a highinterface resistance is preferably used. However, it is difficult toobtain magnetically soft characteristics, which are required for thefree layer, by only Fe. Therefore, the magnetically soft characteristicscan be improved by adding a magnetic material having excellentmagnetically soft characteristics, such as NiFe, which isferromagnetically coupled, as the ferromagnetic layer FM3.

When the ferromagnetic layer in the stacked structure of ferromagneticlayers/ferromagnetic layers contains Fe or an Fe base alloy, theferromagnetic layer preferably has the fcc structure. Because thestacked structure can be more stable when a metal having the fccstructure, such as CoFe or NiFe, is stacked and because the stackedstructure can have good crystalline properties as a whole to improvemagnetically soft characteristics and reduce fluctuation in spin.However, the bcc structure can also be used.

As a combination of two kinds of ferromagnetic layers, a ferromagneticmaterial having the fcc structure can be combined with a ferromagneticmaterial having the bcc structure. As described above referring to FIG.11, in such a combination, the state of electrons, the shape of theFermi surface, and the distribution of state density of theferromagnetic material having the fcc structure are greatly differentfrom those of the ferromagnetic material having the bcc structure. Forthat reason, it is possible to obtain a considerable screen effect withrespect to conduction electrons, so that it is possible to obtain a highresistance and a high rate of change in MR.

By the way, in the CPP-SV, the scattering of electrons occurs whenconduction electrons pass through the pinned layer P and the free layerF. If the pinned layer P or the free layer F is multilayered, themodulation of band potential based on the multilayered cycle is carriedout. Therefore, the wave number vector of electrons capable of flowingin a direction perpendicular to the plane of the film is restricted inaccordance with the modulation of band potential. The restricted wavenumber varies in accordance with the cycle of the multilayeredstructure. Therefore, the wave number of electrons capable of passingthrough both layers can be greatly restricted by changing themultilayered cycles in the pinned layer P and free layer F. Since thescreen effect itself has the spin dependent effect, it is possible tohold a high spin dependency while maintaining a low transmissionprobability of electrons as a whole. That is, if the stacking cycles inthe pinned layer P and free layer F are intentionally caused to bedifferent from each other, it is possible to realize a CPP-SV capable ofrealizing a high rate of change in MR while maintaining a higherresistance.

On the other hand, the non-magnetic intermediate layer S is preferablyformed of a material, in which the mean free path of conductionelectrons is long, such as Cu (copper), Au (gold) or Ag (silver). Byusing such a material, electrons can varistically conduct between thefirst ferromagnetic layer P and the second ferromagnetic layer F, sothat it is possible to more effectively utilize the scattering effect ofelectrons depending on spin, which is caused by the ferromagneticmaterial. Thus, it is possible to obtain a higher rate of change in MR.Alternatively, the non-magnetic intermediate layer S may be formed of analloy of the above described three kinds of elements. In this case, thecomposition is preferably adjusted so that the crystal lattice constantin the stacked structure can be adjusted to be the optimum value.

As shown by the sectional structure in FIG. 15, the non-magneticintermediate layer S may have the stacked structure of non-magneticlayer S1/non-magnetic layer S2 wherein a material, such as Cu, Au or Ag,is stacked. In this case, if the stacking cycle of the stacked structureof non-magnetic layer S1/non-magnetic layer S2, and the stacking cycleof the pinned layer p or the free layer F are suitably set, the wavenumber vector of electrons capable of flowing through the whole CPP-SVin a direction perpendicular to the plane of the film can be restricted,so that it is possible to realize a CPP-SV capable of realizing a higherresistance and a higher rate of change in MR.

On the other hand, the antiferromagnetic layer A is preferably formed ofa metallic antiferromagnetic material having excellent magnetizationfixed characteristics. Specifically, an antiferromagnetic material, suchas PtMn, NiMn, FeMn or IrMn, may be used. The thickness of theantiferromagnetic layer A is preferably as thin as possible from thestandpoint of electric characteristics. However, if theantiferromagnetic layer A is too thin, the magnetization fixedcharacteristics deteriorate, so that it is required to select such athickness that the blocking temperature does not decrease. For thatreason, the thickness is preferably 5 nm or more.

In addition to the above described construction, a so-called syntheticantiferromagnetic structure may be adopted as illustrated in FIG. 16.This is a structure wherein a pair of ferromagnetic layers FM1 and FM2antiferromagnetically coupled to each other via an antiferromagneticcoupling layer AC are added in any one or both of the first magneticlayer P and the second magnetic layer F. By adopting such a syntheticconstruction, the apparent magnetization can be zero in the pinned layerP, so that the magnetization fixed in the pinned layer P can be morestable. In addition, by decreasing the apparent magnetization in thefree layer F, it is possible to obtain a more sensitive response toexternal magnetic field.

Moreover, in addition to the above described construction, a so-calleddual construction wherein the pinned layer P comprises two layers may beadopted.

On other hand, although any special layers have not been arrangedbetween the electrode EL and the spin-valve film in the above describedexamples, an underlying layer (buffer layer) B is preferably formedbetween the bottom electrode EL1 and the antiferromagnetic layer A asillustrated in FIG. 17 in order to improve smoothness and crystallineproperties when an actual element is formed. In addition, a layer C tobe a protective layer is preferably arranged between the top electrodeEL2 and the free layer F. The underlying layer B and the protectivelayer C are preferably formed of a material having a good wettingproperty, such as Ta (tantalum), Ti (titanium) or Cr (chromium), amaterial having a low electric resistance and a stable fcc structure,such as Cu, Au or Ag, or a stacked structure thereof.

Second Embodiment

FIG. 18 is a conceptual drawing showing a cross-sectional structure ofthe second embodiment of a magnetoresistance effect element according toan aspect of the present invention. In this figure, the same referencenumbers are given to the same elements as those described abovereferring to FIGS. 1 through 17, and the detailed descriptions thereofare omitted.

The magnetoresistance effect element in this embodiment also comprisesan antiferromagnetic layer A, a first magnetic layer P, an non-magneticintermediate layer S and a second magnetic layer F which are stacked ona predetermined substrate in that order, and a sense current I is causedto flow in a direction perpendicular to the plane of the film.Furthermore, the antiferromagnetic layer A, the first magnetic layer P,the non-magnetic intermediate layer S and the second magnetic layer Fconstitute a magnetoresistance effect film.

In addition, in this embodiment, a resistance regulating layer R isinserted into the non-magnetic intermediate layer S.

In this embodiment, although the current I flows from the top electrodeEL2 toward the bottom electrode EL1, the quantity of current is reducedby the resistance regulating layer R. Thus, the probability thatelectrons will pass through the CPP spin-valve structure decreases, sothat it is possible to greatly increase the electric resistance as awhole.

In this embodiment, although it is possible to greatly increase theelectric resistance as a whole since the transmission probability ofelectrons decreases, it is possible to hold a high rate of change in MRsince the scattering effect depending on spin is not damaged.

By the above described effects, it is possible to provide a CPPspin-valve film suitably utilizing an interface resistance and having anappropriate value of resistance though it has a spin-valve construction.

Also in this embodiment, since the magnetization of the pinned layer Pand the magnetization of the free layer F are operated so as to beintegrated, the magnetization can be controlled only by themagnetization fixed of the pinned layer P and the control of themagnetization of one free layer F. Therefore, when the element is usedfor a reading sensor, such as a head, it is possible to realize amagnetic head wherein Barkhausen noises are suppressed.

Also in this embodiment, it is possible to obtain a good value ofresistance and a good rate of change in MR while the total thickness ofthe pinned layer P and free layer F is small. That is, as compared withconventional simple CPP spin-valve constructions, this construction canreduce the simple transmission probability of electrons, increase thevalue of resistance and sufficiently utilize the interface resistance.Therefore, in a region wherein the total Mst of the pinned layer P andfree layer F is small, it is possible to obtain a sufficient value ofresistance and a sufficient rate of change in MR. Specifically, althoughthe thickness of the magnetic material of the pinned layer P and freelayer F must be about 20 nm in conventional constructions, thisembodiment can obtain sufficient characteristics even if the totalthickness of the magnetic layers is 5 nm or less. Thus, the Mst of thefree layer F can be held to be a small value, so that it is possible toform a sensitive spin-valve element.

In addition, since it is also possible to decrease the Mst of the pinnedlayer P, it is possible to improve the magnetization fixedcharacteristics by the antiferromagnetic layer A, so that it is possibleto improve the reliability of the device.

In this embodiment similar to the above described first embodiment, theresistance regulating layer R may be formed of a semimetal, such as Bi,Sb or C, or a so-called zero gap semiconductor, such as ZnSe. In thesematerials unlike insulating materials, conduction electrons exist, butthe density thereof is vary small, so that potential sensed by theconduction electrons is vary small. Specifically, as described above, ametal, such as Cu, has a Fermi potential of about 7 eV, whereas asemimetal has a small Fermi potential of 1 eV or less.

For that reason, if the semimetal or zero gap semiconductor is providedin a metal layer, a large difference in potential level occurs, so thatconduction electrons are reflected. In this construction, sinceconduction electrons also exist in the resistance regulating layer, theconduction probability of conduction electrons is sufficiently largerthan the transmission probability of electrons due to tunnel, so thatthe usual conduction controls the total value of resistance. For thatreason, it is possible to make resistance lower than that in the case ofa ferromagnetic tunnel junction, so that it is possible to obtain a goodelement resistance in a fine junction.

The value of Fermi potential in these materials is preferably in therange of from 1 eV to 0 ev, and more preferably in the range of 0.5 eVto 0 eV. The reason for this has been described above with respect tothe first embodiment.

The resistance regulating layer R in this embodiment may be also formedof Au, Ag or an alloy thereof. However, in this case, it is difficult toform so great difference in potential level, so that it is difficult togreatly increase resistance.

The resistance regulating layer R in this embodiment may be also formedof an insulating material which has a potential barrier having arelatively low height. In this case, since the transmission probabilityof electrons is determined by the tunnel probability, the elementresistance is too high if the barrier height increases. From thisstandpoint, the barrier height is preferably 0.1 eV or less.

The resistance regulating layer R in this embodiment may be formed of aninsulating material having pin holes as described above referring toFIGS. 4 through 6. In this case, the transmission probability ofelectrons is determined by the size and density of pin holes. If thesize of the pin holes is about the mean free path of electrons or less,it is possible to obtain a greater resistance increasing effect. Fromthe standpoint of repeatability of element characteristics, at leastabout 10 pin holes are preferably formed in the area of the element.However, only one pin hole may exist in the element. The ratio of thetotal area of the pin holes to the area of the element is preferably 50%or less in order to increase the element resistance.

In this case, since the transmission probability of electrons isdetermined by the electric conduction through the pin holes, theresistance regulating layer R may be formed of an insulating materialhaving a high barrier height, e.g., Al oxide or Si oxide. However, theresistance regulating layer R may be formed of a material having a lowbarrier height, such as Co oxide, Ni oxide or Cu oxide. Also in thatcase, the electric conduction is controlled by the pin holes.

The thickness of the insulating layer in this embodiment is preferablyset to be in the range of from 0.5 nm to 10 nm in order to facilitatethe formation of the pin holes.

As a method for forming such an insulating layer having pin holes,various methods described above in the first embodiment may be used.That is, the insulating layer may be formed by a method for forming avery thin layer of Al by the sputtering method or the like, and then,exposing the layer of Al to an atmosphere of oxygen for a short periodof time to carry out a natural oxidation. Alternatively, the insulatinglayer may be formed by a method for applying energy to a layer of Al byexposing it to oxygen plasma or irradiating it with oxygen ions oroxygen radicals. Alternatively, a material which is relatively easy tobe oxidized, and a material which is difficult to be oxidized, such asAl—Au, may be simultaneously deposited to form a granular film of Al—Auas a layer to be oxidized, and the formed layer may be exposed toselectively oxidize only Al to form the insulating layer. Alternatively,the oxidized layer having pin holes may be formed by depositing a filmin an atmosphere of oxygen.

As another method for forming such insulating layer having pin holes,regularly arranged pin holes may be formed by the fine patternlithography using the AFM or the like or by the self-organizing. Thedetails thereof are the same as those described above in the firstembodiment.

On the other hand, the resistance regulating layer R in this embodimentis not always required to comprise only one layer, but it may have astacked construction of two or more layers. In addition, a plurality ofresistance regulating layers R, not only one resistance regulating layerR, may be provided in the non-magnetic intermediate layer S. By thusinserting the plurality of resistance regulating layers R into thenon-magnetic intermediate layer S, it is possible to further reduce thesimple transmission probability of electrons, so that it is possible toform a CPP spin-valve element having a higher resistance.

Moreover, the construction in this embodiment may be combined with anyone of the above described various constructions in the first embodimentof the present invention. Thus, it is possible to form a CPP spin-valvefilm having a higher resistance.

In the combination of the second embodiment with the first embodiment,when pin holes are formed while the positions thereof are controlled,the positional relationship between the pin holes H in the resistanceregulating layers R, R1 and R2 is important. That is, the pin holes H inthe respective resistance regulating layers may be positioned at thesame place as illustrated in FIG. 19. Alternatively, the positions ofthe pin holes H in the respective resistance regulating layers may beshifted as illustrated in FIG. 20.

When the positions of the pin holes H are shifted as shown in FIG. 20,it is possible to more effectively reduce the quantity of current, sothat it is possible to form a CPP spin-valve element having a higherresistance.

When the pin holes H are thus formed while the positions thereof arecontrolled, the relationship between the sizes of the pin holes H in therespective resistance regulating layers R, R1 and R2 is also important.In this case, although the sizes of the pin holes H in all of theresistance regulating layers may be equal to each other, the sizes ofthe pin holes H in the resistance regulating layers may be differentfrom each other. That is, if the size of the pin hole H in theresistance regulating layer, which is provided on the upstream side withrespect to the flow of electrons, of the resistance regulating layers R,R1 and R2 is largish, it is possible to effectively reduce the quantityof current, so that it is possible to form a CPP spin-valve elementhaving a higher resistance.

Each of the first and second magnetic layers P and F may also have aconstruction of a ferromagnetic layer, a stacked structure offerromagnetic layer/non-magnetic layer, or a stacked structure offerromagnetic layer/ferromagnetic layer, similar to that described abovein the first embodiment.

The non-magnetic intermediate layer S in the second embodiment of thepresent invention may also have the same stacked construction as thatdescribed above in the first embodiment of the present invention.

The antiferromagnetic layer A in the second embodiment of the presentinvention is also preferably formed of a metallic antiferromagneticmaterial having excellent magnetization fixed characteristics, similarto the first embodiment. Specifically, an antiferromagnetic material,such as PtMn, NiMn, FeMn or IrMn, may be used. The thickness of theantiferromagnetic layer A is preferably as thin as possible from thestandpoint of electric characteristics. However, if theantiferromagnetic layer A is too thin, the magnetization fixedcharacteristics deteriorate, so that it is required to select such athickness that the blocking temperature does not decrease. For thatreason, the thickness is preferably 5 nm or more.

In addition to the above described constructions, one or both of thefirst magnetic layer P and the second magnetic layer F may have aso-called synthetic antiferromagnetic layer structure. Moreover, inaddition to the above described constructions, a so-called dualconstruction wherein the pinned layer P comprises two layers may beadopted. These points are the same as those described above referring toFIG. 16 with respect to the first embodiment.

Referring to Examples, the embodiments of the present invention will bedescribed below in more detail.

Example 1

First, Example 1 of the present invention will be described below.

FIG. 21 is a conceptual drawing showing a cross-sectional constructionof a first example of a magnetoresistance effect element according tothe present invention. In the formation of this magnetoresistance effectelement, a Cu bottom electrode EL1 having a thickness of 500 nm wasfirst stacked on a thermally oxidized silicon (Si) substrate (not shown)by the sputtering method, and the Cu bottom electrode EL1 was formed soas to have a stripe shape having a width of 9 μm by thephotolithography. Then, a CPP-SV 3 μm square was deposited thereon. Theconstruction of the film was as follows.

Ta 5 nm (buffer layer B)/NiFe 2 nm (buffer layer B)/PtMn 15 nm(antiferromagnetic layer A)/CoFe 1 nm (pinned layer P1)/AlOx (resistanceregulating layer R1)/CoFe 5 nm (pinned layer P2)/Cu 3 nm (non-magneticintermediate layer S)/CoFe 5 nm (free layer F)/Cu 2 nm (non-magneticlayer NM1)/AlOx (resistance regulating layer R2)/Cu 2 nm (non-magneticlayer NM2)/Ta 5 nm (protective layer C)

The AlOx layer to be a resistance regulating layer was formed bydepositing Al (aluminum), and then, by exposing the deposited Al to anatmosphere of oxygen to self-oxidize Al. In this example, the Al filmwas deposited so as to have a thickness of 1 nm, and was exposed tooxygen by 1 k Langmuir to form the AlOx having pin holes (not shown).That is, in this example, the AlOx layers having pin holes serves as theresistance regulating layer R1 and R2.

An insulating AlOx film Z was deposited on the above describedspin-valve construction, and a hole 0.1 μm square was formed therein.Then, a Cu (copper) film having a thickness of 500 nm was stackedthereon by the sputtering method, to form a top electrode EL2. In thisexample, with the above described construction, it was possible tomeasure CPP-SV characteristics via the hole 0.1 μm square of theinsulating AlOx film Z.

As the results of measurement at room temperatures, it was possible toobtain an element resistance of 7Ω and a rate of change in resistance of10%. Thus, it was possible to obtain an amount of change in resistanceof 0.7Ω. In addition, it was verified that the pinned layer P wassuitably magnetization-fixed and that the magnetization of the stackedstructure constituting the pinned layer P moved integrally. It was alsoverified that Hc of the free layer F was small and its magnetizationmoved integrally with respect to the external magnetic field.

Comparative Example 1

First, a Cu bottom electrode EL1 having a thickness of 500 nm wasstacked on a thermally oxidized silicon (Si) substrate by the sputteringmethod, and the Cu bottom electrode EL1 was formed so as to have astripe shape having a width of 9 μm by the photolithography. Then, aCPP-SV 3 μm square was deposited thereon. The construction of the filmwas as follows.

Ta 5 nm (buffer layer)/NiFe 2 nm (buffer layer)/PtMn 15 nm(antiferromagnetic layer)/CoFe 5 nm (pinned layer)/Cu 3 nm (non-magneticintermediate layer)/CoFe 5 nm (free layer)/Cu 2 nm (non-magneticlayer)/Ta 5 nm (protective layer)

The same insulating film of AlOx as that shown in FIG. 21 was formedthereon, and a hole 0.1 μm square was formed in AlOx. Then, a Cu filmhaving a thickness of 500 nm was stacked thereon by the sputteringmethod, to form atop electrode. As the results of measurement at roomtemperatures, the element resistance was 3Ω, and the rate of change inresistance was only 3%. That is, in this example, the amount of changein resistance was only 0.09Ω, so that the amount of change was onlyabout ⅛ as large as that in Example 1.

Example 2

Similar to the first example, first, a Cu bottom electrode having athickness of 500 nm was stacked on a thermally oxidized silicon (Si)substrate by the sputtering method, and the Cu bottom electrode wasformed so as to have a stripe shape having a width of 9 μm by thephotolithography. Then, a CPP-SV 3 μm square was deposited thereon. Theconstruction of the film was as follows. Ta 5 nm (buffer layer B)/NiFe 2nm (buffer layer B)/PtMn 15 nm (antiferromagnetic layer A)/CoFe 1 nm(ferromagnetic layer FM1)/AlOx (resistance regulating layer R1)/CoFe 1nm (ferromagnetic layer FM2)/Cu 1 nm (non-magnetic layer NM1)/CoFe 1 nm(ferromagnetic layer FM3)/Cu 1 nm (non-magnetic layer NM2)/CoFe 1 nm(ferromagnetic layer FM4)/Cu 3 nm (non-magnetic intermediate layerS)/CoFe 1 nm (ferromagnetic layer FM5)/Cu 1 nm (non-magnetic layerNM3)/CoFe 1 nm (ferromagnetic layer FM6)/Cu 1 nm (non-magnetic layerNM4)/CoFe 1 nm (ferromagnetic layer FM7)/Cu 2 nm (non-magnetic layerNM5)/AlOx (resistance regulating layer R2)/Cu 2 nm (non-magnetic layerNM6)/Ta 5 nm (protective layer C)

In the above described stacked structure, the stacked layers from theferromagnetic layer FM1 to the ferromagnetic layer FM constitute apinned layer P, and the stacked layers from the ferromagnetic layer FM5to the ferromagnetic layer FM7 constitute a free layer F.

The AlOx layers constituting the resistance regulating layers R1 and R2were formed as AlOx layers having pin holes by the same method as thatin Example 1.

Similar to FIG. 21, an insulating AlOx film was deposited on the abovedescribed spin-valve construction, and a hole 0.1 μm square was formedtherein. Then, a Cu film having a thickness of 500 nm was stackedthereon by the sputtering method, to form a top electrode EL2. In thisexample, with the above described construction, it was possible tomeasure CPP-SV characteristics via the hole 0.1 μm square of theinsulating AlOx film.

As the results of measurement at room temperatures, it was possible toobtain an element resistance of 9Ω and a rate of change in resistance of20%. That is, it was possible to obtain an amount of change inresistance of 1.8Ω. In addition, it was verified that the pinned layer Pwas suitably magnetization-fixed and that the magnetization of the pinstacked structure moved integrally. It was also verified that Hc of thefree layer F was small and its magnetization moved integrally withrespect to the external magnetic field.

Third Embodiment

Referring to FIG. 31, the third embodiment of the present invention willbe described below. FIG. 31 is a conceptual drawing showing across-section of the third embodiment of a magnetoresistance effectelement according to an aspect of the present invention. As shown inFIG. 31, the magnetoresistance effect element in this embodimentcomprises a bottom electrode 31, an underlying layer 32, anantiferromagnetic layer 33, a magnetization fixed layer 34, annon-magnetic intermediate layer 35, a magnetization free layer 36, anon-magnetic metal layer 37, a non-magnetic compound layer 38 and a topelectrode 39, which are stacked in that order. Furthermore, theantiferromagnetic layer 33, the magnetization fixed layer 34, thenon-magnetic intermediate layer 35 and the magnetization free layer 36constitute a magnetoresistance effect film.

The non-magnetic compound layer 38 is formed of at least one selectedfrom the group consisting of oxides, nitrides, borides and carbides ofB, Si, Ge, Ta, W, Nb, Al, Mo, P, V, As, Sb, Zr, Ti, Zn, Pb, Th, Be, Cd,Sc, La, Y, Pr, Cr, Sn, Ga, Cu, In, Rh, Pd, Mg, Li, Ba, Ca, Sr, Mn, Fe,Co, Ni and Rb. The non-magnetic compound layer 38 is preferablycrystalline. Materials easy to obtain crystalline include oxides whichcontain at least one selected from the group consisting of B, Si, Ge, W,Nb, Mo, P, V, Sb, Zr, Ti, Zn, Pb, Cr, Sn, Ga, Fe and Co. Throughout thespecification, the term “crystalline” means that the non-magneticcompound layer is single crystal or polycrystal, and does not mean astate wherein microcrystals are scattered in amorphous. This can beeasily verified by observing a lattice image by means of across-sectional TEM (Transmission Electron Microscopy) or the like. Forexample, if an orderly arrangement is observed, it can be said that itis crystalline. Alternatively, if a spot-like pattern is observed in anelectron beam diffraction image, it can be determined that a rangeirradiated with electron beams is substantially single crystal to becrystalline. If a ring-shaped pattern is obtained, it can be determinedthat a range irradiated with electron beams is in a polycrystallinestate to be crystalline. The state of the epitaxial growth from thebottom layer can be verified by observing the lattice image.

The non-magnetic compound layer 38 allows its pseudo thickness to beincreased by the electron reflecting effect, so that it is possible toincrease the output. If the non-magnetic compound layer 38 includes ametal phase, a semimetal phase and a half metal phase or has pin holes,it cause current to be contracted, and causes the current density to beeffectively increased. Therefore, the output increases. If theproportion of the non-magnetic phase to the metal phase is too large,the resistance is too high, so that the heat generation of the elementincreases to deteriorate the characteristics of the element. Therefore,in order to obtain the above described effects, the proportion of themetal layer portion is 2% or more. On other hand, if the metal phaseportion is too large, the function of increasing the current densitydecreases, so that the proportion of the metal phase portion ispreferably 30% or less.

The presence of the metal phase or pin hole portion in the layer can beverified by observing the lattice image by the cross-sectional TEM. Thatis, if a portion epitaxially connected to the upper and lower metalphases exists, it can be said that this portion is a metal phase. If acomponent analysis in the non-magnetic layer is carried out, thepresence of a metal phase can be verified. That is, if the concentrationof oxygen, nitrogen, fluorine or boron is less than 20% by compositionratio, it can be said that it is substantially a metal phase.

The mean diameter of such a metal phase portion or pin hole portion ispreferably in the range of 10% to 100% with respect to the totalthickness of the magnetization free layer, non-magnetic intermediatelayer and magnetization fixed layer. If it is 10% or less, the increaseof resistance due to contraction is too large, so that this is notpractical. On the other hand, if it is 100% or more, the current is toobroad, so that the contraction effect can not be obtained. In the caseof a structure (synthetic antiferromagnetic structure) that themagnetization fixed layer is antiferromagnetically coupled via anon-magnetic metal layer such as Ru, the total thickness must becalculated in view of only the ferromagnetic layer nearer to thenon-magnetic intermediate layer.

The distance between such metal phase portions or pin hole portions onthe plane of the film is preferably in the range of from 1 nm to 100 nm.If it is 1 nm or less, the current having been contracted once overlapswith each other in the vicinity of the non-magnetic compound layer, sothat the effect deteriorates. On the other hand, if it is 100 nm ormore, the number of the portions existing in the actual element is about1 through 3, so that the variation in characteristics is stochasticallyincreased.

If the non-magnetic compound layer 38 is amorphous, the rapidity ofelectron potentials on the interface of the film is lost, and theelastic scattering is inhibited. Therefore, it is not possible to obtainso great electron reflecting effect, so that the increase of the outputcan not be expected. In addition, the non-magnetic compound layer 38 isamorphous, its structure is unstable, and its heat resistancedeteriorates, so that the deterioration of the output is caused. Inorder to obtain a crystalline non-magnetic compound layer, a compoundselected from the group consisting of oxides of rare earth metals, e.g.,B, Si, Ge, W, Nb, Mo, P, V, Sb, Zr, Ti, Zn, Pb, Cr, Sn, Ga, Fe and Co,is preferably used.

The thickness of the non-magnetic compound layer 38 must be 0.2 nm ormore since its shape is easily changed by the thermal diffusion if thethickness is 0.2 nm or less. On the other hand, if the thickness is 10nm or more, the resistance of the element increases, and when a sensecurrent is caused to flow, excessive head is generated to cause thedeterioration of the output. The thickness of the non-magnetic compoundlayer 38 is more preferably in the range of from 0.5 mm to 5 nm.However, it should not be limited thereto if the non-magnetic compoundlayer 38 is made of a compound of a semimetal, a half metal or a metal.

The non-magnetic metal layer 37 is preferably made of an element havinglow reactivity, in order to stabilize the compound of the non-magneticcompound layer 38. From this standpoint, a metal layer containing atleast one selected from the group consisting of Cu, Au, Ag, Ru, Ir, Re,Rh, Pt, Pd, and Os is effective. Al can be used as the non-magneticmetal layer 37. In this case, the non-magnetic compound layer 38 ispreferably made of a material which is easily oxidizable than Al.Comparing the non-magnetic metal layer 37 with the non-magnetic compoundlayer 38, the non-magnetic compound layer 38 is preferably made of acompound mainly containing an element which is different from theelement of the non-magnetic metal layer 37. Because it is difficult tohold the thermostability of the non-magnetic compound layer 38 sinceoxygen is easy to diffuse if the bond energies of oxygen, nitrogen,carbon and boron are equal to each other. However, it is possible toproduce a compound, which is very resistant to diffusion, by some methodfor preparing the compound. For example, the compound prepared byirradiating a metal layer with ions, plasma or radicals of an element tobe combined is very stable, and does not exhibit so considerablediffusion between the compound phase and metal phase of the same kind ofmetallic element. Moreover, combinations of the above described compoundlayer of a compound prepared by irradiating a metal layer with producedions, plasma and radicals, and the above described non-magnetic metallayer containing at least one selected from the group consisting of Cu,Au, Ag, Ru, Ir, Re, Rh, Pt, Pd, Al, and Os, are very thermostable.

The non-magnetic compound layer 38 is not always required to be formedas a layer, but it may be formed in the non-magnetic metal layer 37 asislands as shown in FIG. 32. In this case, the materials of thenon-magnetic metal layer 32 and the non-magnetic compound are the sameas those in FIG. 31. The distance between such island-like compounds onthe plane of the film is preferably in the range of from 1 nm to 100 nm.If it is 1 nm or less, the current having been contracted once overlapswith each other in the vicinity of the non-magnetic compound layer, sothat the effect deteriorates. On the other hand, if it is 100 nm ormore, the number of the portions existing in the actual element is about1 through 3, so that the variation in characteristics is stochasticallyincreased. In addition, the ratio of the area of the island-like portionto the metal portion therebetween on the plane of the film is preferablyin the range of from 2% to 30%.

In order to form the metal phase portion in the non-magnetic compoundlayer or in order to form the structure having pin holes, materialshaving different oxidation energies may be combined. In particular, thematerial forming the metal phase portion preferably mainly contains theabove described metal containing at least one selected from the groupconsisting of Cu, Au, Ag, Ru, Ir, Re, Rh, Pt, Pd, Al, and Os. In thiscase, if atoms forming the non-magnetic compound layer diffuse into themetal phase portion, there is the possibility that the resistance of themetal phase portion increases to cause practical problems. For thatreason, the atoms forming the metal phase and the atoms forming thecompound phase are not substantially soluble.

For example, if the main component of the metal phase portion is Cu, themain component forming the non-magnetic compound layer is preferably atleast one selected from the group consisting of B, Fe, Mo, Pb, Ta, Cr,V, Si, Sb and Ge, and more preferably at least one selected from thegroup consisting of B, Fe, Mo, Pb, Cr, V, Si, Sb and Ge which are easyto be crystalline.

For example, if the main component of the metal phase portion is Au, themain component forming the non-magnetic compound layer is preferably atleast one selected from the group consisting of B, Fe, Ge, Mo, P, Rh,Si, W and Cr, and more preferably at least one selected from the groupconsisting of B, Fe, Mo, P, Si, W and Cr which are easy to becrystalline.

For example, if the main component of the metal phase portion is Ag, themain component forming the non-magnetic compound layer is preferably atleast one selected from the group consisting of B, Be, Co, Cr, Fe, Mo,Pb, Si, Ta, V, W, Ge, Sn, Al and Rh, and more preferably at least oneselected from the group consisting of B, Be, Co, Cr, Fe, Mo, Pb, Si, V,W, Ge, Sn, Al and Rh which are easy to be crystalline.

For example, if the main component of the metal phase portion is Pt, themain component forming the non-magnetic compound layer is preferably W.

For example, if the main component of the metal phase portion is Pd, themain component forming the non-magnetic compound layer is preferably Wor Cr.

As a method for forming the above described combination of the metalphase and the non-magnetic compound phase, the non-magnetic compound maybe formed in the layer or on the interface of the material forming themetal phase. The non-magnetic compound may be formed by feeding areaction gas after deposition, or the non-magnetic compound may bedirectly stacked by sputtering or the like.

As another method for forming the above described combination of themetal phase and the non-magnetic compound phase, the non-magneticcompound may be formed by feeding a reactive gas after forming an alloylayer of the material forming the metal phase and the material formingthe non-magnetic compound layer. Such an alloy layer may be formed by,e.g., stacking an alloy target by sputtering or the like. The alloytarget may be prepared by the above described combination of thenon-solid-solution materials. Although the target is non soluble, thetarget may be prepared by sintering, or may be a mosaic of twomaterials.

The bottom electrode 31 is formed of a metal containing a materialselected from the group consisting of Cu, Au, Ag, Ru, Ir, Re, Rh, Pt,Pd, Al, Os and Ni. The underlying layer 32 is formed of NiFeCr,Ta/NiFeCr, Ta/Ru, Ta/NiFe, Ta/Cu, or Ta/Au. The stacked structure of Taand fcc or a metal layer of HCP is important in order to obtain a goodfilm growth. In particular, in order to obtain good magnetically softcharacteristics of the magnetization free layer, it is important toobtain the (111) orientation of the fcc structure, and it is required toprovide the above described structure of the underlayer 32.

Also in this embodiment, it is possible to obtain a CPP typemagnetoresistance effect element which has an appropriate value ofresistance and a large amount of change in MR and which is magneticallysensitive.

Fourth Embodiment

Referring to FIG. 33, the fourth embodiment of the present inventionwill be described below. FIG. 33 is a conceptual drawing showing across-section of the fourth embodiment of a magnetoresistance effectelement according to an aspect of the present invention. Themagnetoresistance effect element in this embodiment comprises a bottomelectrode 31, an underlying layer 32, an antiferromagnetic layer 33, amagnetization fixed layer 34, an non-magnetic intermediate layer 35, amagnetization free layer 36, a non-magnetic metal layer 37, anon-magnetic compound layer 38 and a top electrode 39, which are stackedin that order. Furthermore, the antiferromagnetic layer 33, themagnetization fixed layer 34, the non-magnetic intermediate layer 35 andthe magnetization free layer 36 constitute a magnetoresistance effectfilm.

The non-magnetic intermediate layer 35 is in a mixed state with thenon-magnetic compound layer 38. As shown in FIG. 34, the non-magneticcompound layer 38 may be deposited in the non-magnetic intermediatelayer 35 or may be granular. The non-magnetic compound layer 38 may passthrough the non-magnetic intermediate layer 35 in a directionperpendicular to the plane of the film (see FIG. 35). The non-magneticcompound layer 38 is no always required to be arranged in thenon-magnetic intermediate layer 35, but it may be formed on theinterface (see FIG. 36). By preparing such a structure, it is possibleto effectively decrease the element size to increase the currentdensity, so that it is possible to increase the output. There is alsosuch a current contracting effect if the non-magnetic compound layer38-is arranged on the magnetization free layer 36 on the opposite sideto the non-magnetic intermediate layer 35 as described in the thirdembodiment. However, the contracting effect is stronger if thenon-magnetic compound layer 38 is formed at the substantially center ofa portion, which is related directly to the magnetoresistance effect, asthis embodiment. If the non-magnetic compound layer 38 is amorphous,thermodiffusion may be caused to have a bad influence on the mean freepath in the non-magnetic intermediate layer 35. For that reason, thenon-magnetic compound layer 38 is preferably crystalline. If theproportion of the non-magnetic compound layer 38 to the metal phase istoo great, the resistance is too high, so that the heat generation ofthe element increases to deteriorate the characteristics of the element.For that reason, the proportion of the metal layer portion is 2% ormore. On other hand, if the metal phase portion is too large, thefunction of increasing the current density decreases, so that theproportion of the metal phase portion is preferably 30% or less.

The presence of the metal phase or pin hole portion in the layer can beverified by observing the lattice image by the cross-sectional TEM. Thatis, if a portion epitaxially connected to the upper and lower metalphases exists, it can be said that this portion is a metal phase. If acomponent analysis in the non-magnetic compound layer is carried out,the presence of a metal phase can be verified. That is, if theconcentration of oxygen, nitrogen, fluorine or boron is less than 20% bycomposition ratio, it can be said that it is substantially a metalphase.

However, in order to obtain good magnetoresistance effect, it isimportant that electrons pass through the non-magnetic intermediatelayer without being scattered. For that reason, the concentration ofoxygen, nitrogen, fluorine or boron is preferably less than 15% bycomposition ratio.

The mean diameter of such a metal phase portion or pin hole portion ispreferably in the range of 10% to 100% with respect to the totalthickness of the magnetization free layer, non-magnetic intermediatelayer and magnetization fixed layer. If it is 10% or less, the increaseof resistance due to contraction is too large, so that this is notpractical. On the other hand, if it is 100% or more, the current is toobroad, so that the contraction effect can not be obtained. In the caseof a structure (synthetic antiferromagnetic structure) that themagnetization fixed layer is antiferromagnetically coupled via anon-magnetic metal layer such as Ru, the total thickness must becalculated in view of only the ferromagnetic layer nearer to thenon-magnetic intermediate layer.

The distance between such metal phase portions or pin hole portions onthe plane of the film is preferably in the range of from 1 nm to 100 nm.If it is 1 nm or less, the current having been contracted once overlapswith each other in the vicinity of the non-magnetic compound layer, sothat the effect deteriorates. It is more preferably the distance is 10nm or more. On the other hand, if it is 100 nm or more, the number ofthe portions existing in the actual element is about 1 through 3, sothat the variation in characteristics is stochastically increased.

In order to form the metal phase portion in the non-magnetic compoundlayer or in order to form the structure having pin holes, materialshaving different oxidation energies may be combined. In particular, thematerial forming the metal phase portion in the non-magnetic compoundlayer preferably mainly contains the above described metal containing atleast one selected from the group consisting of Cu, Au, Ag, Ru, Ir, Re,Rh, Pt, Pd, Al and Os. In this case, if atoms forming the non-magneticcompound layer diffuse into the metal phase portion, there is thepossibility that the resistance of the metal phase portion increases tocause practical problems. For that reason, the atoms forming the metalphase and the atoms forming the compound phase are not substantiallysoluble.

For example, if the main component of the metal phase portion is Cu, themain component forming the non-magnetic compound layer is preferably atleast one selected from the group consisting of B, Fe, Mo, Pb, Ta, Cr,V, Si, Sb and Ge, and more preferably at least one selected from thegroup consisting of B, Fe, Mo, Pb, Cr, V, Si, Sb and Ge which are easyto be crystalline.

For example, if the main component of the metal phase portion is Au, themain component forming the non-magnetic compound layer is preferably atleast one selected from the group consisting of B, Fe, Ge, Mo, P, Rh,Si, W and Cr, and more preferably at least one selected from the groupconsisting of B, Fe, Mo, P, Si, W and Cr which are easy to becrystalline.

For example, if the main component of the metal phase portion is Ag, themain component forming the non-magnetic compound layer is preferably atleast one selected from the group consisting of B, Be, Co, Cr, Fe, Mo,Pb, Si, Ta, V, W, Ge, Sn, Al and Rh, and more preferably at least oneselected from the group consisting of B, Be, Co, Cr, Fe, Mo, Pb, Si, V,W, Ge, Sn, Al and Rh which are easy to be crystalline.

For example, if the main component of the metal phase portion is Pt, themain component forming the non-magnetic compound layer is preferably W.

For example, if the main component of the metal phase portion is Pd, themain component forming the non-magnetic compound layer is preferably Wor Cr.

As a method for forming the above described combination of the metalphase and the non-magnetic compound phase, the non-magnetic compound maybe formed in the layer or on the interface of the material forming themetal phase. The non-magnetic compound may be formed by feeding areaction gas after deposition, or the non-magnetic compound may bedirectly stacked by sputtering or the like.

As another method for forming the above described combination of themetal phase and the non-magnetic compound phase, the non-magneticcompound may be formed by feeding a reactive gas after forming an alloylayer of the material forming the metal phase and the material formingthe non-magnetic compound layer. Such an alloy layer may be formed by,e.g., stacking an alloy target by sputtering or the like. The alloytarget may be prepared by the above described combination of thenon-solid-solution materials. Although the target is non soluble, thetarget may be prepared by sintering, or may be a mosaic of twomaterials.

Also in this embodiment, it is possible to obtain a CPP typemagnetoresistance effect element which has an appropriate value ofresistance and a large amount of change in MR and which is magneticallysensitive.

Fifth Embodiment

As the fifth embodiment of the present invention, a magnetic head usinga magnetoresistance effect element according to an aspect of the presentinvention will be described below.

FIG. 22 is a schematic perspective view of a principal part of amagnetic head using a magnetoresistance effect element according to theembodiment of the present invention. That is, the magnetic headaccording to the embodiment of the present invention has a pair ofmagnetic yokes 102, 102 which are arranged so as to face a recordingmedium 200. On the magnetic yokes 102, 102, a magnetoresistance effectelement 104 magnetically coupled thereto is provided. Themagnetoresistance effect element 104 is any one of the CPP type elementsaccording to embodiments of the present invention, which have beendescribed above referring to FIGS. 1 through 21 and FIGS. 31 through 34.On both sides thereof, a pair of bias layers 106, 106 are formed so asto straddle the pair of magnetic yokes 102, 102. The bias layers 106 aremade of an antiferromagnetic or ferromagnetic material, and have thefunction of directing the magnetization of the magnetic yoke 102 and thefree layer of the magnetoresistance effect element 104 to a directionperpendicular to a recording magnetic field, i.e., to the y direction inthe figure.

In the recording medium 200, a recording track 200 T is formed, andrecording bits 200B are arranged. In each of the recording bits 200B, asignal magnetization illustrated by arrows is formed. The signalmagnetic flux from these recording bits is given to a magnetic circuitwhich connects the magnetic yokes 102 to the magnetoresistance effectelement 104. If the magnetic field of the recording bit 200B is given tothe magnetoresistance effect element 104, the magnetization of the freelayer rotates on the plane from the y direction due to the bias layer106. Then, the variation in magnetizing direction is detected as thevariation in magnetic resistance.

In order to match the magnetic detection region of the magnetoresistanceeffect element 104 to the size of the recording bit 200B, the contact ofthe electrode of the magnetoresistance effect element 104 is formed soas to be limited to a region corresponding to a recording track width Wshown in FIG. 22.

According to the embodiment of the present invention, any one of the CPPtype elements described above referring to FIGS. 1 through 21 and FIGS.31 through 34 is used as the magnetoresistance effect element 104, sothat it is possible to obtain both an appropriate element resistance anda large variation in magnetic resistance. That is, it is possible torealize a magnetic head having a greatly higher sensitive and morestable reliability than those of conventional heads.

While the magnetic head suitable for magnetic recording media of alongitudinal (in-plane) recording system has been described in thisembodiment, the present invention should not be limited thereto. Themagnetoresistance effect element according to an aspect of the presentinvention may be applied similarly to a magnetic head suitable forvertical recording media, to obtain the same effects.

Sixth Embodiment

As the sixth embodiment of the present invention, a magnetic recordingand/or reproducing system using a magnetoresistance effect elementaccording to an aspect of the present invention will be described below.Any one of the magnetoresistance effect elements according toembodiments of the present invention, which have been described abovereferring to FIGS. 1 through 21 and FIGS. 31 through 34, can be mountedon a magnetic head illustrated in FIG. 22, and can be incorporated in,e.g., a recording/reproducing integral type magnetic head assembly, tobe applied to a magnetic recording and/or reproducing system.

FIG. 23 is a perspective view illustrating a schematic construction of aprincipal part of such a magnetic recording and/or reproducing system.That is, a magnetic recording and/or reproducing system 150 according toan aspect of the present invention is a system of a type using a rotaryactuator. In this figure, a longitudinal recording or vertical recordingmagnetic disk 200 is mounted on a spindle 152, and is rotated in adirection of arrow A by means of a motor (not shown) which responds to acontrol signal from a drive unit control part (not shown). A head slider153 for recording/reproducing information to be stored in the magneticdisk 200 is mounted on the tip of a thin-film-like suspension 154. Forexample, a magnetic head including any one of the magnetoresistanceeffect elements according to embodiments of the present invention, whichhave been described in Example 6, is provided in the vicinity of the tipof the head slider 153.

If the magnetic disk 200 rotates, the medium facing surface or airbearing surface (ABS) of the head slider 153 is held at a predeterminedflying height from the surface; of the magnetic disk 200.

The suspension 154 is connected to one end of an actuator arm 155 whichhas a bobbin portion or the like for holding a driving coil (not shown).On the other hand of the actuator arm 155, a voice coil motor 156 whichis a kind of a linear motor is provided. The voice coil motor 156comprises: a driving coil (not shown) wound onto the bobbin portion ofthe actuator arm 155; and a magnetic circuit comprising permanentmagnets, which are arranged so as to face each other via the coil, andfacing yokes.

The actuator arm 155 is held by two ball bearings (not shown) which areprovided above and below a fixing shaft 157, and is rotatable andslidable by means of the voice coil motor 156.

FIG. 24 is an enlarged perspective view of a magnetic head assembly infront of an actuator arm 155, which is viewed from the side of a disk.That is, the magnetic head assembly 160 has an actuator arm 151 having,e.g., a bobbin portion or the like for holding a driving coil, and asuspension 154 is connected to one end of the actuator arm 155.

A head slider 153 having a reproducing magnetic head using amagnetoresistance effect element according to embodiments of the presentinvention is mounted on the tip of the suspension 154. A recording headmay be combined. The suspension 154 has a lead wire 164 for writing andreading signals. This lead wire 164 is electrically connected to eachelectrode of the magnetic head which is incorporated in the head slider153. In the figure, reference number 165 denotes an electrode pad of themagnetic head assembly 160.

Between the medium facing surface or air bearing surface (ABS) of thehead slider 153 and the surface of the magnetic disk 200, apredetermined flying height is set.

The slider 153 including the magnetic head 10 operates while flying at apredetermined height from the surface of the magnetic disk 200.According to an aspect of the present invention, such a “flyingtraveling type” magnetic recording and/or reproducing system can alsoreproduce at low noises with a higher resolution than conventionalsystems.

On the other hand, of course, a “contact traveling type” magneticrecording and/or reproducing system for traveling the slider whilepositively causing the magnetic head 10 to contact the magnetic disk 200can also reproduce at low noises with a higher resolution thanconventional systems.

Referring to Examples, the embodiments of the present invention havebeen described. However, the present invention should not be limited tothese examples.

For example, with respect to the structure of the spin-valve element andthe materials of the respective layers, the present invention may besimilarly applied to all embodiments, which can be selected by personswith ordinary skill in the art, to provide the same effects. Forexample, the present invention can be similarly applied to a “dual type”structure.

In addition, the structure of the magnetic head, the materials andshapes of the respective elements constituting the magnetic head shouldnot be limited to those described above in Examples, but the presentinvention may be similarly applied to all embodiments, which can beselected by persons with ordinary skill in the art, to provide the sameeffects.

The magnetic recording and/or reproducing system may be a reproducingonly system or a recording and/or reproducing system. In addition, themedium should not be limited to a hard disk, but it may be any one ofall magnetic recording media, such as flexible disks and magnetic cards.Moreover, the magnetic recording and/or reproducing system may be aso-called “removable” type system wherein a magnetic recording medium isremoved from the system.

Moreover, a magnetoresistance effect element according to an aspect ofthe present invention can be combined with a transistor/diode or thelike, or used alone, to form a “magnetic memory cell” for storingmagnetic information. That is, the present invention can be applied to a“magnetic random access memory (MRAM)” comprising integrated magneticmemory cells.

As described above in detail, according to the present invention, it ispossible to provide a CPP type magnetoresistance effect element whichhas an appropriate value of resistance and a large amount of change inMR and which is magnetically sensitive.

As a result, it is possible to surely read magnetic information from afiner recording bit from that in conventional elements, so that it ispossible to greatly improve the packing density of a recording medium.Simultaneously, the reliability of the magnetic recording and/orreproducing system is improved due to thermal stability, and theutilized scope thereof is extended, so that there is a great industrialmerit.

While the present invention has been disclosed in terms of theembodiment in order to facilitate better understanding thereof, itshould be appreciated that the invention can be embodied in various wayswithout departing from the principle of the invention. Therefore, theinvention should be understood to include all possible embodiments andmodification to the shown embodiments which can be embodied withoutdeparting from the principle of the invention as set forth in theappended claims.

1. A magnetoresistance effect element comprising: a magnetoresistanceeffect film including a magnetization fixed layer having a ferromagneticfilm in which the direction of magnetization is substantially fixed toone direction, a magnetization free layer having a ferromagnetic film inwhich the direction of magnetization varies in response to an externalmagnetic field, and a non-magnetic intermediate layer provided betweenthe magnetization fixed layer and the magnetization free layer; a pairof electrodes which are electrically connected to the magnetoresistanceeffect film and configured to apply a current in a directionperpendicular to the plane of the magnetoresistance effect film; and aresistance regulating layer containing an oxide, a nitride, a fluoride,a carbide or a boride, the resistance regulating layer formed in thenon-magnetic intermediate layer or on the interface between thenon-magnetic intermediate layer and at least one of the magnetizationfixed layer and the magnetization free layer.
 2. The magnetoresistanceeffect element according to claim 1, wherein the ferromagnetic film ofthe magnetization fixed layer comprises a stacked structure which has atleast a non-magnetic layer and two first magnetic layers sandwiching thenon-magnetic layer, the first magnetic layers are antiferromagneticcoupled via the non-magnetic layer.
 3. The magnetoresistance effectelement as set forth in claim 1, wherein the non-magnetic layer has afilm thickness of 2 nm or less.
 4. The magnetoresistance effect elementas set forth in claim 1, wherein the ferromagnetic film of at least oneof the magnetization fixed layer and the magnetization free layercomprises at least a second magnetic layer formed of Fe or an Fe basealloy.
 5. The magnetoresistance effect element as set forth in claim 1,wherein the ferromagnetic film of at least one of the magnetizationfixed layer and the magnetization free layer contains at least oneselected from the group consisting of FeNi, FeCo, FeSi, FeMo, and FeAl.6. The magnetoresistance effect, element according to claim 1, whereinthe ferromagnetic film of at least one of the magnetization fixed layerand the magnetization free layer is formed of a Co base alloy andcontains at least one selected from the group consisting of Fe, Ni, Au,Ag, Cu, Pd, Pt, Ir, Rh, Ru, Os, and Hf as an additional element.
 7. Themagnetoresistance effect element according to claim 1, wherein thenon-magnetic layer contains at least one selected from the groupconsisting of Cu, Ag, Au, Rh, Ru, Mn, Cr, Re, Os, and Ir.
 8. Themagnetoresistance effect element according to claim 1, wherein theresistance regulating layer has a hole or holes provided with metaltherein, two adjacent layers which contact the resistance regulatinglayer have an electric conduction substantially limited to conductionthrough the hole of the resistance regulating layer.
 9. Themagnetoresistance effect element according to claim 8, wherein theresistance regulating layer has holes of metal phase of 2% to 30%. 10.The megnetoresistance effect element according to claim 8, wherein themean diameter of each of the holes of the resistance regulating layer isin the range from 10% to 100% with respect to the total thickness of themagnetization free layer, the non-magnetic intermediate layer, and themagnetization fixed layer.
 11. The magnetoresistance effect elementaccording to claim 8, wherein a concentration of oxygen, nitrogen,fluorine or boron in the resistance regulating layer is less than 20% bycomposition ratio.